Syncope: evaluation, risk stratification and management

Overview and definitions

ESC 2018 asks first whether the event was TLOC at all, and then whether it was of syncopal or non-syncopal origin.^[1] ESC 2018 defines TLOC as a state of real or apparent loss of consciousness (LOC) with loss of awareness, characterised by amnesia for the period of unconsciousness, abnormal motor control, loss of responsiveness and a short duration.^[1]

ESC 2018 divides TLOC into TLOC due to head trauma and non-traumatic TLOC.^[1] ESC 2018 classifies non-traumatic TLOC into four groupings, in order of how often they occur: syncope, epileptic seizures, psychogenic TLOC and a miscellaneous group of rare causes.^[1] ESC 2018 separates the groups by mechanism: cerebral hypoperfusion for syncope, abnormal excessive brain activity for epileptic seizures and the psychological process of conversion for psychogenic TLOC.^[1]

ESC 2018 uses the adjective presyncope for symptoms and signs that occur before unconsciousness in syncope, and notes that the noun is often used for a state resembling the prodrome of syncope that is not followed by LOC.^[1] ACC/AHA/HRS 2017 defines presyncope (near-syncope) as the symptoms before syncope, which could progress to syncope or abort without it.^[2]

Related terms (ACC/AHA/HRS 2017)

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Classification

ESC 2018 states that the efficacy of therapy to prevent recurrence is largely determined by the mechanism of syncope rather than its aetiology.^[1] ESC 2018 Table 3 groups the principal causes by common pathophysiology, presentation and risk.^[1]

Classification of syncope (ESC 2018 Table 3)

^[1]

ESC 2018 Table 3 adds that hypotension may be exacerbated by venous pooling during exercise, after meals (postprandial hypotension) and after prolonged bed rest.^[1] ESC 2018 names two mechanisms in reflex syncope: vasodepression, when insufficient sympathetic vasoconstriction causes hypotension, and cardioinhibition, when bradycardia or asystole predominates.^[1]

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Epidemiology

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ACC/AHA/HRS 2017 describes a trimodal distribution in both sexes, with the first episode common around 20, 60 or 80 years of age and the third peak 5 to 7 years earlier in males.^[2] In a cross section of 1925 randomly selected Olmsted County residents, all older than 45 years, ACC/AHA/HRS 2017 reports an estimated lifetime syncope prevalence of 19%, with a higher prevalence reported by females (22% versus 15%).^[2] ACC/AHA/HRS 2017 reports that older institutionalised patients have a 7% annual incidence of syncope, a 23% overall prevalence and a 30% 2-year recurrence rate.^[2]

ESC 2018 gives a composite estimate of outcomes after an ED visit for syncope: in the next 7–30 days, only 0.8% die and 6.9% have a non-fatal severe outcome while in the ED, and another 3.6% have a post-ED serious outcome.^[1] ESC 2018 also states that OH is associated with a two-fold higher risk of death, owing to the severity of comorbidities, compared with the general population.^[1]

Pathophysiology

ESC 2018 centres the classification on a fall in systemic BP with a decrease in global cerebral blood flow, and shows low BP with global cerebral hypoperfusion as the final common pathway of syncope.^[1] ESC 2018 states that a sudden cessation of cerebral blood flow for as short as 6–8 s can cause complete LOC.^[1] ESC 2018 states that a systolic BP of 50–60 mmHg at heart level, that is 30–45 mmHg at brain level in the upright position, will cause LOC.^[1]

ESC 2018 frames the haemodynamics simply: systemic BP is the product of cardiac output and total peripheral resistance, a fall in either can cause syncope, and in syncope both mechanisms often act together.^[1]

^[1]

ESC 2018 Figure 3 places drug-induced, primary and secondary autonomic failure in its outer ring, and ESC 2018 Table 3 lists drug-induced OH, the most common cause of OH, as its own entry, separate from primary autonomic failure and secondary autonomic failure (neurogenic OH).^[1]

ESC 2018 notes that these mechanisms may interact: venous pooling can trigger an inappropriate reflex in orthostatic reflex syncope, and a low total peripheral resistance may cause venous pooling below the diaphragm that lowers venous return and cardiac output.^[1] ESC 2018 adds that in autonomic failure there is insufficient sympathetic vasoconstriction in response to the upright position, and that reflex syncope and OH both span the two main mechanisms.^[1]

ACC/AHA/HRS 2017 describes the pathophysiology of VVS as a reflex causing hypotension and bradycardia, triggered by prolonged standing or exposure to emotional stress, pain or medical procedures.^[2] ACC/AHA/HRS 2017 explains that in neurogenic OH the vasoconstrictor mechanisms of vascular tone may be inadequate because of neurodegenerative disorders or autonomic peripheral neuropathies, such as those due to diabetes mellitus and other systemic diseases.^[2]

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Clinical presentation

ESC 2018 Table 5 lists clinical features that can suggest a diagnosis on initial evaluation.^[1]

Clinical features that can suggest a diagnosis on initial evaluation (ESC 2018 Table 5)

^[1]

ACC/AHA/HRS 2017 Table 4 lists historical characteristics associated with, though not diagnostic of, cardiac and noncardiac syncope.^[2]

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Differential diagnosis

ESC 2018 Table 4 lists the main features that distinguish syncope from disorders that may be mistaken for it.^[1] ESC 2018 states that epilepsy forms in which people remain upright, such as complex partial seizures or absence epilepsy, are not regarded as TLOC but are sometimes misdiagnosed as syncope.^[1]

Conditions that may be incorrectly diagnosed as syncope (ESC 2018 Table 4)

^[1]

Initial evaluation

ESC 2018 frames the initial evaluation as four questions: was the event TLOC; if so, is it syncopal or non-syncopal; in suspected syncope, is there a clear aetiological diagnosis; and is there evidence to suggest a high risk of cardiovascular events or death?^[1] ESC 2018 states that a detailed clinical history lets physicians differentiate syncope from other forms of TLOC in approximately 60% of cases.^[1]

^[1]

ACC/AHA/HRS 2017 recommends a detailed history and physical examination in patients with syncope (COR I, LOE B-NR) and calls a resting 12-lead ECG useful in the initial evaluation (COR I, LOE B-NR).^[2] ACC/AHA/HRS 2017 supporting text says the examination should include orthostatic BP and heart rate lying, sitting, on immediate standing and after 3 minutes upright.^[2] ACC/AHA/HRS 2017 supporting text also asks for a family history, with particular emphasis on syncope or sudden unexplained death (or drowning).^[2]

ESC 2018 states that, based on the findings of the initial evaluation, additional examinations may be performed when needed.^[1]

• Immediate ECG monitoring when there is a suspicion of arrhythmic syncope.^[1]
• Echocardiogram when there is previous known heart disease, data suggestive of structural heart disease, or syncope secondary to cardiovascular cause.^[1]
• Carotid sinus massage (CSM) in patients aged >40 years (ESC 2018; the newer ESC 2021 CSM row names no age, see Carotid sinus massage below).^[1][4]
• Head-up tilt testing when there is suspicion of syncope due to OH or reflex syncope (ESC 2018; for suspected recurrent reflex syncope, the newer ESC 2021 tilt row applies, see Tilt testing below).^[1][4]
• Blood tests when clinically indicated, e.g. haematocrit or haemoglobin for suspected haemorrhage, oxygen saturation and blood gas for suspected hypoxia, troponin for suspected cardiac ischaemia-related syncope, or D-dimer for suspected pulmonary embolism.^[1]

When the initial evaluation is diagnostic (ESC 2018)

Diagnostic criteria with initial evaluation (ESC 2018 recommendation table)

^[1]

ESC 2018 states that when a diagnosis is nearly certain or highly likely, no further evaluation is needed and treatment, if any, can be planned.^[1] ESC 2018 adds that in young subjects with unexplained syncope, no cardiac history, no family history of sudden death, no supine, sleep or exercise syncope, no unusual triggers and a normal ECG, the chance of cardiac syncope is very low.^[1]

Orthostatic BP: active standing

Active standing (ESC 2018 recommendation table)

^[1]

ESC 2018 notes that its OH definition differs from the 2011 consensus by adding the absolute 90 mmHg systolic threshold, which it considers useful especially when supine BP is below 110 mmHg.^[1] ESC 2018 states that the orthostatic HR increase is blunted or absent (usually not >10 b.p.m.) in neurogenic OH, but increases or even exaggerates with anaemia or hypovolaemia.^[1]

ACC/AHA/HRS 2017 defines OH as a drop in systolic BP of ≥20 mm Hg or diastolic BP of ≥10 mm Hg with assumption of an upright posture.^[2] ACC/AHA/HRS 2017 also defines three subtypes by timing.^[2]

• Initial (immediate) OH (ACC/AHA/HRS 2017): a transient BP decrease within 15 s after standing, with presyncope or syncope.^[2]
• Classic OH (ACC/AHA/HRS 2017): a sustained reduction of systolic BP of ≥20 mm Hg or diastolic BP of ≥10 mm Hg within 3 min of assuming upright posture.^[2]
• Delayed OH (ACC/AHA/HRS 2017): a sustained reduction of systolic BP of ≥20 mm Hg (or 30 mm Hg in patients with supine hypertension) or diastolic BP of ≥10 mm Hg that takes >3 min of upright posture to develop.^[2]
• Neurogenic OH (ACC/AHA/HRS 2017): a subtype of OH due to dysfunction of the autonomic nervous system and not solely due to environmental triggers such as dehydration or drugs.^[2]

Association of orthostatic intolerance and orthostatic hypotension (ESC 2018 Table 8)

^[1]

ESC 2018 Table 8 calls a history highly suggestive of OH when syncope and presyncope occur while standing, are absent lying and less severe or absent sitting, with a predilection for the morning.^[1] In the same ESC 2018 Table 8 definition, sitting or lying down must help, complaints may get worse immediately after exercise, after meals or in high temperatures, and there is no autonomic activation.^[1]

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Risk stratification

ESC 2018 gives two reasons for risk stratification: to recognise patients with a likely low-risk condition who can be discharged with adequate patient education, and patients with a likely high-risk cardiovascular condition who need urgent investigation, which may require admission.^[1] ESC 2018 states that high-risk patients are more likely to have cardiac syncope, while low-risk patients are more likely to have reflex syncope and have an excellent prognosis.^[1]

ESC 2018: Table 6 features at initial evaluation in the ED

High-risk features (that suggest a serious condition) and low-risk features (that suggest a benign condition) at initial evaluation in the ED (ESC 2018 Table 6)

^[1]

A footnote to ESC 2018 Table 6 states that some ECG criteria are per se diagnostic of the cause of syncope, and that appropriate therapy is then indicated without further investigations.^[1]

ACC/AHA/HRS 2017: short- and long-term risk factors

ACC/AHA/HRS 2017 recommends evaluation of the cause and assessment of the short- and long-term morbidity and mortality risk of syncope (COR I, LOE B-NR).^[2] ACC/AHA/HRS 2017 groups current data into short-term risk (outcomes in the ED and up to 30 days after syncope) and long-term risk (up to 12 months of follow-up).^[2]

Short- and long-term risk factors (ACC/AHA/HRS 2017 Table 5); history rows first, then examination and laboratory rows

^[2]

A footnote to ACC/AHA/HRS 2017 Table 5 states that definitions of clinical endpoints or serious outcomes vary by study.^[2] A footnote to ACC/AHA/HRS 2017 Table 6 (examples of syncope risk scores) notes that abnormal ECG is defined variably in those studies.^[2] The same ACC/AHA/HRS 2017 Table 6 footnote defines an abnormal ECG in syncope evaluation as any rhythm other than normal sinus rhythm, conduction delays (BBB, type 2 second-degree AV block or third-degree AV block), Q waves, ST abnormalities or a prolonged QT interval.^[2]

Risk scores

ESC 2018 states that risk stratification scores may be considered for risk stratification in the ED (Class IIb, Level B).^[1] ESC 2018 also advises that the scores perform no better than good clinical judgement and should not be used alone to perform risk stratification in the ED.^[1] ACC/AHA/HRS 2017 states that use of risk stratification scores may be reasonable in managing patients with syncope (COR IIb, LOE B-NR).^[2]

Emergency department management and disposition

ESC 2018 says ED management of suspected syncope should answer three questions: is there a serious underlying cause that can be identified, what is the risk of a serious outcome, and should the patient be admitted?^[1] ESC 2018 states that the acute underlying disease, rather than the syncope itself, most frequently determines short-term adverse events.^[1] ESC 2018 adds that many (40–45%) non-cardiovascular and some cardiovascular life-threatening underlying conditions are obvious in the ED.^[1]

Management of syncope in the emergency department (ESC 2018 recommendation table)

^[1]

• ESC 2018, low-risk patients: they do not need further diagnostic tests in the ED, as they are likely to have reflex, situational or orthostatic syncope.^[1]
• ESC 2018, high-risk patients: they need an intensive diagnostic approach and may need urgent treatment and admission; they should be monitored where resuscitation can be performed; ESC 2018 says it is unclear for how long, with most studies suggesting up to 6 hours in the ED and up to 24 hours in hospital.^[1]
• ESC 2018, neither high- nor low-risk: these patients require expert syncope opinion, which can probably be safely managed in an outpatient setting.^[1]
• ESC 2018, presyncope: in the ED, presyncope should be managed with the same accuracy as syncope, as it carries the same prognosis.^[1]
• ESC 2018, devices: to reduce inappropriate admissions, patients with a cardiac device and syncope should undergo prompt device interrogation.^[1]
• ESC 2018, routine tests: diagnostic radiology and laboratory tests such as chest X-ray, brain computed tomography, routine blood haematology, biochemistry, D-dimer and cardiac markers have a low diagnostic yield and impact on risk stratification, and should not routinely be used unless specifically suggested by clinical evaluation.^[1]

ESC 2018 Table 7 lists criteria in high-risk patients that favour a stay in an ED observation unit and/or fast-tracking to a syncope unit versus requiring admission to hospital.^[1]

High-risk syncope patients: observation unit or fast-track versus admission (ESC 2018 Table 7)

^[1]

ESC 2018 warns that unnecessary admission in low-risk patients can be harmful, and that not all patients at high risk need hospitalisation.^[1] For patients with neither high- nor low-risk features, ESC 2018 (Figure 6 legend) finds no direct evidence that hospital admission changes outcome, but evidence that management in an ED observation unit and/or fast-track to a syncope outpatient unit is beneficial.^[1]

ACC/AHA/HRS 2017: disposition after initial evaluation

Disposition after initial evaluation (ACC/AHA/HRS 2017 recommendation table)

^[2]

ACC/AHA/HRS 2017 states that individual risk factors and risk scores are not primary determinants for admission; the presence of at least one serious medical condition in its Table 7 is the key determinant for further in-hospital management.^[2]

Examples of serious medical conditions that might warrant consideration of further evaluation and therapy in a hospital setting (ACC/AHA/HRS 2017 Table 7)

^{[2] [1] [2]}

Investigations

ECG monitoring

ESC 2018 states that ECG monitoring is indicated only when there is a high pre-test probability of identifying an arrhythmia associated with syncope, such as those in its Table 5.^[1] ESC 2018 calls the correlation between symptoms and an ECG recording the gold standard for diagnosing arrhythmic syncope.^[1]

Electrocardiographic monitoring (ESC 2018 recommendation table)

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Monitoring when bradycardia is suspected (ESC 2021 pacing guideline)

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Where bradycardia is suspected, these ESC 2021 rows are the newer rows; the ESC 2018 rows above cover syncope more generally and are given alongside them.^[4][1]

• ESC 2018, presyncope: without a documented arrhythmia, presyncope cannot be considered a surrogate for syncope, whereas a significant arrhythmia documented at the time of presyncope can be considered diagnostic.^[1]
• ESC 2018, a normal recording: the absence of arrhythmia during syncope excludes arrhythmic syncope.^[1]
• ESC 2018, patience: because syncope recurrence is unpredictable, be prepared to wait up to 4 years or more for a symptom–ECG correlation.^[1]
• ESC 2018, limitation: no ECG monitor records BP, so in reflex syncope documented bradycardia or asystole during a syncopal episode does not rule out the possibility that a hidden hypotensive reflex is the principal cause.^[1]

^[1]

Cardiac monitoring and in-hospital telemetry (ACC/AHA/HRS 2017 recommendation tables)

^[2]

ACC/AHA/HRS 2017 Table 8 fits the Holter monitor to symptoms frequent enough to be detected within 24–72 h of monitoring.^[2] ACC/AHA/HRS 2017 Table 8 fits the implantable cardiac monitor to recurrent, infrequent, unexplained syncope (or suspected atypical reflex syncope) of suspected arrhythmic cause after a nondiagnostic initial workup, with or without structural heart disease.^[2]

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Tilt testing

Tilt testing (ESC 2021 pacing guideline)

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Tilt testing (ESC 2018 recommendation table; for suspected recurrent reflex syncope its first row is dated by the ESC 2021 row above)

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For suspected recurrent reflex syncope, the current ESC row among the guidelines checked for this topic is the ESC 2021 row (Class IIa, Level B); the ESC 2018 row is history for that group.^[4][1] The ESC 2021 row sits in that guideline’s section on evaluating suspected or documented bradycardia or conduction system disease.^[4] ESC 2021 text says tilt testing should be considered to confirm a diagnosis of reflex syncope in patients in whom this diagnosis was suspected but not confirmed by initial evaluation.^[4] For other suspected reflex syncope, and for OH, POTS and PPS, none of the newer ESC guidelines checked for this topic has a tilt-testing row, so the ESC 2018 row is given as current.^[1][4]

• ESC 2018: a negative tilt table response does not exclude a diagnosis of reflex syncope.^[1]
• ESC 2018: in syncope of uncertain origin, tilt testing suggests a hypotensive susceptibility, which may exist in reflex syncope and in other causes, including some forms of cardiac syncope.^[1]
• ESC 2018: a positive cardioinhibitory response predicts, with high probability, asystolic spontaneous syncope; a vasodepressor, mixed or even negative response does not exclude asystole during spontaneous syncope.^[1]
• ESC 2018: tilt testing should not be used to assess the efficacy of a drug treatment.^[1]

ESC 2018 cites a systematic literature review: overall tilt positivity in patients with syncope was 66% with the trinitroglycerin protocol and 61% with isoproterenol, against 11–14% in controls, and the test separated patients with syncope from controls with an odds ratio of 12.^[1] ESC 2018 also reports positivity of 45–47% in true cardiac arrhythmic syncope, and states that tilt testing should now be considered a means of exposing a hypotensive tendency rather than being diagnostic of VVS.^[1]

Tilt-table testing (ACC/AHA/HRS 2017 recommendation table)

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Carotid sinus massage

Carotid sinus massage (ESC 2021 pacing guideline, non-invasive evaluation table)

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The ESC 2021 footnote says CSM should not be undertaken after a previous TIA or stroke, or with known carotid stenosis.^[4] The same footnote adds that the carotids should be auscultated first, and that a carotid bruit calls for carotid ultrasound to exclude carotid disease.^[4] ESC 2018 had indicated CSM in patients >40 years of age with syncope of unknown origin compatible with a reflex mechanism (Class I, Level B).^[1] The ESC 2018 CSM row is history here: the ESC 2021 row names no age and adds symptoms related to pressure on or manipulation of the carotid sinus area.^[4][1] ESC 2021 text adds that CSM can be helpful in any patient ≥40 years old with symptoms suggestive of carotid sinus syndrome (CSS): syncope or near syncope elicited by tight collars, shaving or turning the head.^[4]

Diagnosis of carotid sinus syndrome (ESC 2018 carotid sinus massage recommendation table, selected row)

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ESC 2018 defines carotid sinus hypersensitivity as a ventricular pause lasting >3 s and/or a fall in systolic BP of >50 mmHg, and notes it is common in older men without syncope.^[1] ESC 2018 states that a history of syncope reproduced by CSM defines CSS, whereas a positive CSM without a history of syncope defines carotid sinus hypersensitivity.^[1] ESC 2018 advises performing CSM supine and upright with continuous beat-to-beat BP monitoring.^[1] ESC 2018 had advised only caution after previous TIA or stroke or with known carotid stenosis >70%; the newer ESC 2021 footnote says CSM should not be undertaken after previous TIA or stroke, or with known carotid stenosis.^[1][4]

ESC 2018 reports TIAs or strokes in 21 of 8720 patients (0.24%) in pooled data from four studies of CSM.^[1]

Echocardiography, exercise testing and electrophysiological study

Cardiac tests after the initial evaluation (selected formal recommendation rows)

^{[1] [2] [5] [4]}

ESC 2021 indicates a pacemaker in unexplained syncope with bifascicular block when EPS shows a baseline His ventricular (HV) interval ≥70 ms, second- or third-degree intra- or infra-Hisian block during incremental atrial pacing, or an abnormal response to pharmacological challenge (Class I, Level B).^[4] For bifascicular block, the ESC 2021 row replaces the ESC 2018 row, which said EPS should be considered in patients with syncope and bifascicular BBB when syncope remains unexplained after non-invasive evaluation (Class IIa, Level B).^[1][4] For unexplained syncope after previous STEMI, and in DCM or HNDCM, the ESC 2022 rows above replace the ESC 2018 EPS row.^[1][5] ESC 2022 also has disease-specific rows on PES or electrophysiological evaluation, which are not limited to unexplained syncope; selected rows follow.^[5] In arrhythmogenic right ventricular cardiomyopathy (ARVC) with symptoms highly suspicious for ventricular arrhythmia, PES may be considered for risk stratification (Class IIb, Level C).^[5] After repair of tetralogy of Fallot (TOF) with arrhythmia symptoms and non-sustained VT (NSVT), electrophysiologic evaluation including PES should be considered (Class IIa, Level C).^[5] These two ESC 2022 rows set their own entry criteria (symptoms highly suspicious for ventricular arrhythmia in ARVC; arrhythmia symptoms and NSVT after TOF repair) rather than unexplained syncope, so they are given beside the ESC 2018 EPS row.^[1][5] In myotonic dystrophy with palpitations or syncope suggestive of ventricular arrhythmia, or after surviving a cardiac arrest, invasive electrophysiological evaluation is recommended (Class I, Level C).^[5] This row also sets its own entry criteria (palpitations or syncope suggestive of ventricular arrhythmia, or a survived cardiac arrest) rather than syncope that remains unexplained after non-invasive evaluation, so it too is given beside the ESC 2018 EPS row.^[5][1] In cardiac sarcoidosis with LVEF 35–50% and minor late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) after resolution of acute inflammation, PES for risk stratification should be considered (Class IIa, Level C).^[5] That row names no symptoms, so it is given beside the ESC 2018 EPS row.^[5][1] For syncope after other myocardial infarction and in other scar-related conditions, the current row is the ESC 2018 row: EPS is indicated when syncope remains unexplained after non-invasive evaluation (Class I, Level B).^[1][5] No newer row indicating EPS for syncope that remains unexplained in these other groups was found in the ESC guidelines checked for this topic.^[1] The ESC 2020 adult congenital heart disease guideline has a tetralogy of Fallot section on indications for electrophysiological testing and implantable cardioverter defibrillator.^[10] In that section, ESC 2020 supporting text says that patients with unexplained syncope and impaired ventricular function or other risk factors for sudden cardiac death should undergo haemodynamic and electrophysiological evaluation.^[10] For congenital heart disease (CHD), this topic gives two ESC 2022 Recommendation Table 38 rows.^[5] One is the TOF row above.^[5] The other, in the ICD table below, is on ICD implantation in CHD with presumed arrhythmic syncope and either at least moderate ventricular dysfunction or inducible sustained monomorphic VT (SMVT) on PES (Class IIa, Level C).^[5] In its section on post-infarct patients with preserved or mildly reduced ejection fraction, ESC 2022 supporting text also recommends PES when syncope remains unexplained after non-invasive evaluation, to guide patient management.^[5] ACC/AHA/HRS 2017 notes that EPS has a limited role, especially without known heart disease or with low suspicion of an arrhythmic cause.^[2]

Blood tests and neurological tests

Blood and neurological tests (selected formal recommendation rows)

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ACC/AHA/HRS 2017 states that the evidence suggests routine neurological testing is of very limited value in syncope, with a low diagnostic yield and a very high cost per diagnosis.^[2]

Management: reflex syncope

ESC 2018 calls non-pharmacological treatment the cornerstone of reflex syncope care, including education, lifestyle modification and reassurance about the benign nature of the condition.^[1] ACC/AHA/HRS 2017 states that, given the benign nature of VVS and its frequent remissions, medical treatment is usually not required unless conservative measures are unsatisfactory.^[2]

ESC 2018 states that additional treatment may be necessary in severe forms, in particular when very frequent syncope alters quality of life, or when recurrent syncope without or with a very short prodrome exposes the patient to a risk of trauma.^[1] ESC 2018 also lists syncope during a high-risk activity (e.g. driving, machine operation, flying or competitive athletics) as a situation in which additional treatment may be necessary.^[1] ESC 2018 states that age is the most important discriminant for the choice of therapy, with younger patients aged under 40 years and older patients over 60 years, and an overlap between 40 and 60 years.^[1]

Treatment of reflex syncope: non-pacing rows (ESC 2018 recommendation table, selected rows)

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Pacing for reflex syncope (ESC 2021 pacing and cardiac resynchronisation therapy guideline recommendation table)

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The 2021 ESC pacing guideline states that, since the 2018 ESC syncope guideline, trials have added information on tilt-induced asystolic vasovagal syncope.^[4] It concludes that sufficient evidence exists to upgrade from IIb to I the indication for pacing in patients aged >40 years with asystolic tilt response >3 s.^[4] In patients aged >40 years, the 2018 ESC syncope guideline had graded pacing to reduce syncopal recurrences IIa, B for spontaneous documented symptomatic asystolic pause(s) >3 s or asymptomatic pause(s) >6 s due to sinus arrest, AV block or both.^[1] In the same age group with recurrent frequent unpredictable syncope, it had graded pacing to reduce syncope recurrences IIa, B for cardioinhibitory carotid sinus syndrome and IIb, B for tilt-induced asystolic response.^[1] The single ESC 2021 row above grades all three Class I, Level A.^[4] ESC 2018 text had already limited pacing in reflex syncope to highly selected patients aged ≥40 years (mostly >60 years).^[1] It describes them as affected by severe forms of reflex syncope with frequent recurrences associated with a high risk of injury, often due to the lack of prodrome.^[1]

ESC 2018 describes the education package as reassurance, awareness and possible avoidance of triggers such as dehydration or hot crowded places, and early recognition of the prodrome so the patient can sit or lie down and start counter-pressure manoeuvres.^[1] ESC 2018 explains that isometric muscle contractions increase cardiac output and arterial BP during impending reflex syncope.^[1]

ESC 2018 calls careful avoidance of BP-lowering agents (antihypertensives, nitrates, diuretics, neuroleptic antidepressants or dopaminergic drugs) key to preventing recurrence.^[1] ESC 2018 states that there is moderate evidence that reducing hypotensive therapy, targeting a systolic BP of 140 mmHg, should reduce recurrences in patients with hypotensive susceptibility.^[1]

ESC 2018 states that midodrine (usually 2.5–10 mg, three times daily) has proved effective in small studies, but none satisfied the criteria of a definitive clinical trial.^[1] ESC 2018 adds that a systematic review rated confidence in the estimates as moderate because of imprecision and publication bias.^[1] In the ESC 2018 account of POST 2, 210 young patients (median age 30 years) with low–normal BP and without comorbidities were randomised to fludrocortisone (titrated at 0.05–0.2 mg once per day) or placebo.^[1] In POST 2, as ESC 2018 reports it, the primary endpoint showed only a marginal, non-significant reduction in syncope with fludrocortisone compared with placebo (hazard ratio 0.69, 95% CI 0.46–1.03).^[1] ESC 2018 reports that beta-blockers failed to be effective in VVS in two randomised double-blind controlled trials, and may enhance bradycardia in CSS.^[1]

Expected syncope recurrence with a permanent pacemaker (ESC 2018 Table 9)

^[1]

ESC 2018 explains why: cardiac pacing is the most powerful therapy for bradycardia, but its efficacy is less if hypotension coexists.^[1]

ESC 2018 states that syncopal recurrences often decrease spontaneously after medical assessment, even without specific therapy; in general, syncope recurs in fewer than 50% of patients within 1–2 years.^[1]

Vasovagal syncope and pacemakers in VVS (ACC/AHA/HRS 2017 recommendation tables)

^[2]

ACC/AHA/HRS 2017 supporting text, for recurrent VVS without a clear contraindication, suggests 2 to 3 L of fluid per day and a total of 6 to 9 g (100 to 150 mmol) of salt per day.^[2] ACC/AHA/HRS 2017 supporting text reports that, in a meta-analysis of 5 RCTs in adults and children, midodrine was associated with a 43% reduction in syncope recurrence.^[2] The ACC/AHA/HRS 2017 rows on selective serotonin reuptake inhibitors and beta blockers in VVS give no doses.^[2]

ACC/AHA/HRS 2017 supporting text reports no statistically significant benefit with active pacing in 2 RCTs.^[2] The same ACC/AHA/HRS 2017 text reports that dual-chamber pacing reduced syncope recurrence in a select population of patients >40 years with recurrent syncope and documented spontaneous pauses ≥3 seconds correlated with syncope or an asymptomatic pause ≥6 seconds.^[2] ACC/AHA/HRS 2017 supporting text on pacing in VVS reports less benefit from dual-chamber pacing in patients whose positive tilt-table test induced a vasodepressor response.^[2]

Carotid sinus syndrome (ACC/AHA/HRS 2017 recommendation table)

^{[2] [1] [4] [2]}

Management: orthostatic hypotension

Treatment of orthostatic hypotension (ESC 2018 recommendation table)

^{[1] [8]}

ESC 2018 text advises, in the absence of hypertension, 2–3 L of fluids per day and 10 g of sodium chloride.^[1] ESC 2018 states that rapid ingestion of cool water is reported to be effective in combating orthostatic intolerance and postprandial hypotension.^[1] ESC 2018 explains that head-up sleeping prevents nocturnal polyuria, keeps a more favourable distribution of body fluids and ameliorates nocturnal hypertension.^[1]

Managing hypertension in patients with orthostatic hypotension (ESC 2024 hypertension guideline, Recommendation Table 24)

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ESC 2024 adds in its text that the treatment of orthostatic hypotension among those with supine hypertension is not to automatically down-titrate BP-lowering medications.^[8] It adds that reversible causes should be sought and treated (including discontinuation of offending medications), and that patients requiring BP-lowering medication should be switched to BP-lowering medications that are less likely to cause orthostatic hypotension.^[8] For BP-lowering medications in OH with supine hypertension, the second ESC 2024 row above replaces the ESC 2018 drug-modification row (Class IIa, Level B).^[8][1] ESC 2018 names the vasoactive drugs as any antihypertensive agents, nitrates, diuretics, neuroleptic antidepressants, or dopaminergic drugs.^[1] For the other hypotensive drugs, such as nitrates, neuroleptic antidepressants or dopaminergic drugs, the ESC 2018 row is given as current.^[1] The same holds for OH without supine hypertension: no newer drug row specific to orthostatic hypotension was found in the ESC guidelines checked for this topic.^[1] For very old or frail patients whose BP drops, see also the ESC 2024 deprescription row under Older patients.^[8]

BP threshold and target with pre-treatment symptomatic orthostatic hypotension (ESC 2024 hypertension guideline, Recommendation Tables 17 and 18, selected rows)

^[8]

These two ESC 2024 rows set the BP threshold for starting BP-lowering treatment and the on-treatment BP target in hypertension.^[8] They are not rows on the treatment of orthostatic hypotension or syncope.^[8]

ESC 2018 states that the principal strategy in drug-induced autonomic failure is eliminating the offending agent.^[1]

Neurogenic OH, dehydration and drugs (ACC/AHA/HRS 2017 recommendation tables)

^[2]

ACC/AHA/HRS 2017 adds that syncope in POTS is relatively infrequent, and there is little evidence that the syncope is due to POTS.^[2]

Management: cardiac syncope

ESC 2018 states that, even in the absence of specific trials, there is strong consensus that with syncope secondary to structural cardiac disease the goal of treatment is not only to prevent recurrence but to treat the underlying disease and decrease the risk of death.^[1] ESC 2018 notes that therapy to prevent recurrence often differs from therapy for the underlying disease.^[1]

Pacing for bradycardia and conduction disease (ESC 2021 pacing and cardiac resynchronisation therapy guideline; selected rows from its sinus node dysfunction, atrioventricular block, bundle branch block and suspected-syncope recommendation tables)

^[4]

A footnote to the ESC 2021 sinus-rhythm AVB row states that, in asymptomatic narrow QRS complex and 2:1 AVB, pacing may be avoided if supra-Hisian block is clinically suspected (concomitant Wenckebach is observed and block disappears with exercise) or demonstrated at EPS.^[4] These ESC 2021 rows replace the bradycardia and conduction-disease pacing rows of the ESC 2018 syncope guideline, one of them only in part (below).^[1][4] For example, ESC 2018 had graded pacing IIa, C when the relationship between syncope and asymptomatic sinus node dysfunction was less established.^[1][4] The row replaced only in part is the ESC 2018 Class I, Level C row indicating pacing in intermittent or paroxysmal intrinsic third- or second-degree AV block, including AF with slow ventricular conduction, although there is no documentation of a correlation between symptoms and ECGs.^[1] For second-degree type 1 AV block that is not shown to cause symptoms and is not intra- or infra-Hisian, no newer recommendation row was found in the ESC guidelines checked for this topic.^[1][4] The same holds for AF with slow ventricular conduction without third- or high-degree AV block.^[1][4] ESC 2021 text, which carries no class or level, states that the indications for pacing are the same for paroxysmal as for permanent AV block.^[4] The reasons it gives are the risk of syncope and sudden cardiac death and the potential progression to permanent AV block.^[4] For AV block in permanent AF, ESC 2021 text states that, in the absence of a potentially reversible cause, bradycardia or inappropriate chronotropic response associated or reasonably correlated with symptoms is an indication for cardiac pacing.^[4] The same text adds that, in the absence of symptoms due to bradycardia and of high-degree or infranodal block, pacing is unlikely to be beneficial and is not indicated.^[4] So for these groups the ESC 2018 row is still the newest recommendation row, but the newer ESC 2021 text ties pacing to symptoms or to the type and level of AV block.^[1][4]

Treatment of syncope due to tachyarrhythmias (ESC 2018 recommendation table, selected rows)

^{[1] [5] [9] [7]}

The newer ESC 2019 SVT guideline has no Class/Level recommendation row specific to syncope; its rows include catheter ablation and drug therapy for specific SVTs.^[9] For example, catheter ablation is recommended for symptomatic, recurrent atrioventricular nodal re-entrant tachycardia (AVNRT) (Class I, Level B).^[9] Catheter ablation of the accessory pathway(s) is recommended in patients with symptomatic, recurrent atrioventricular re-entrant tachycardia (AVRT) (Class I, Level B).^[9] For chronic therapy of AVNRT, diltiazem or verapamil (in patients without heart failure with reduced ejection fraction) or beta-blockers should be considered if ablation is not desirable or feasible (Class IIa, Level B).^[9] This topic does not reproduce the other ESC 2019 SVT rows.

ESC 2022 grades catheter ablation and antiarrhythmic drugs (AADs) for VT within its substrate-specific recommendation tables, for example chronic coronary artery disease (CAD) in Recommendation Table 24 and DCM/HNDCM in Recommendation Table 28.^[5] In chronic CAD, the ESC 2022 Class I, Level B ablation row applies to recurrent, symptomatic sustained monomorphic VT (SMVT), or ICD shocks for SMVT, despite chronic amiodarone therapy.^[5] In that setting, ablation is recommended in preference to escalating AAD therapy; the other catheter ablation rows in Recommendation Table 24 are Class IIa or IIb.^[5]

Catheter ablation and antiarrhythmic drugs for VT by substrate (ESC 2022 ventricular arrhythmia guideline, selected rows from its chronic CAD and DCM/HNDCM recommendation tables)

^[5]

The ESC 2022 chronic CAD row on catheter ablation as an alternative to an ICD in haemodynamically well-tolerated SMVT with LVEF ≥40% is given in the ICD table below.^[5] So are the ESC 2022 Recommendation Table 12 rows on amiodarone or catheter ablation for patients with an ICD indication when an ICD is not available, contraindicated for concurrent medical reasons, or declined by the patient.^[5] ESC 2022 has further rows on treating ventricular arrhythmias in its other substrate tables, for example idiopathic premature ventricular complexes/VT (Recommendation Table 26), hypertrophic cardiomyopathy (Table 30), cardiac sarcoidosis (Table 35) and congenital heart disease (Table 39).^[5] For arrhythmogenic right ventricular cardiomyopathy, the newer ESC 2023 cardiomyopathy guideline has its own antiarrhythmic table (Recommendation Table 28).^[7] Rows on the acute management of sustained VT and electrical storm are in ESC 2022 Recommendation Table 9.^[5] This topic does not reproduce the rows in the tables named in the last three sentences.

ICD after a documented ventricular arrhythmia (ESC 2022, 2023 and 2026 recommendation tables, selected rows)

^{[5] [7] [6]}

ESC 2026 heart failure refers secondary-prevention ICD to the 2022 ventricular arrhythmia guideline, and cardiomyopathy-specific recommendations for secondary-prevention ICD to the 2023 cardiomyopathy guideline.^[6]

ESC 2018 defines unexplained syncope, for patients at high risk of sudden cardiac death, as syncope that does not meet any Class I diagnostic criterion in its section 4 recommendation tables.^[1] ESC 2018 states that patients with unexplained syncope and an established ICD indication must receive an ICD before, and independently of, evaluation of the mechanism of syncope.^[1]

Primary-prevention ICD rows in CAD, DCM, NDLVC and CHD (ESC 2022 and ESC 2023, selected rows)

^{[5] [7]}

ESC 2023 defines the non-dilated LV cardiomyopathy phenotype as non-ischaemic LV scarring or fatty replacement without LV dilatation, with or without wall motion abnormalities.^[7] The same definition includes isolated global LV hypokinesia without scarring, unexplained solely by abnormal loading conditions (hypertension, valve disease) or CAD.^[7] ESC 2022 notes that a new category of hypokinetic non-dilated cardiomyopathy (HNDCM) has been proposed, and its recommendation table covers DCM and HNDCM together.^[5] ESC 2023 proposes replacing the term hypokinetic non-dilated cardiomyopathy with non-dilated left ventricular cardiomyopathy (NDLVC), so the NDLVC rows above are the ESC 2023 rows for non-dilated hypokinetic disease.^[7] ESC 2023 adds that its recommendations for ICD implantation in DCM with LVEF <35% also apply to patients with NDLVC and LVEF <35%.^[7]

Earlier ESC ICD and ILR rows that newer ESC rows cover only in part (current for patients outside the newer rows)

^{[1] [5] [7] [6]}

ESC 2022 and ESC 2023 also have disease-specific tables on sudden cardiac death prevention.^[5][7] Examples are ARVC (ESC 2022 Recommendation Table 29; ESC 2023 Recommendation Table 29), hypertrophic cardiomyopathy (ESC 2022 Table 30; ESC 2023 Table 23), neuromuscular diseases (ESC 2022 Table 33) and cardiac sarcoidosis (ESC 2022 Table 35).^[5][7] Some of their rows on ICD implantation apply to patients in the groups above; for ARVC and hypertrophic cardiomyopathy, the ESC 2023 tables are the newer source of sudden cardiac death prevention rows.^[7][5] For example, for primary prevention in patients with ARVC, ESC 2023 says high-risk features should be considered to aid individualised decision-making for ICD implantation (Class IIa, Level B).^[7] A footnote to that ESC 2023 row lists the high-risk features as arrhythmic syncope, NSVT, right ventricular ejection fraction (RVEF) <40%, LVEF <45% and SMVT at PES.^[7] ESC 2022 says ICD implantation is recommended in cardiac sarcoidosis with LVEF ≤35% (Class I, Level B).^[5] This topic names these tables but does not reproduce them.^[5][7]

Two ESC 2026 heart failure Class III rows also cover part of these groups.^[6] ICD implantation for primary prevention is not recommended within 40 days of a myocardial infarction, as implantation during this period does not improve prognosis (Class III, Level B1).^[6] ICD implantation is not recommended in NYHA class IV with severe symptoms refractory to pharmacological therapy, unless the patient is a candidate for cardiac resynchronisation therapy, a ventricular assist device or heart transplantation (Class III, Level C).^[6]

ESC 2022 Figure 15, its algorithm for chronic CAD with reduced ejection fraction, contains boxes for NSVT or unexplained syncope, PES, inducible SMVT and ICD implantation (Class IIa).^[5] The figure is an algorithm, not a recommendation-table row, so the table above does not count it as a newer row.^[5] For post-infarct patients with preserved or mildly reduced LVEF, ESC 2022 supporting text states that there are no data supporting primary prophylactic ICD implantation.^[5]

Earlier ESC ICD rows (selected), given here only as dated history

^{[1] [5] [7] [6]}

Primary-prevention ICD in heart failure (ESC 2026 heart failure guideline recommendation table, selected rows; levels as printed)

^[6]

The ESC 2026 rows above separate ischaemic from non-ischaemic aetiology.^[6] The ESC 2018 syncope guideline row they replace recommended ICD therapy to reduce SCD in symptomatic heart failure (NYHA class II–III) with LVEF ≤35% after ≥3 months of optimal medical therapy.^[1] That row was limited to patients expected to survive ≥1 year with good functional status and was Class I, Level A without separating aetiology.^[1] Before ESC 2026, the 2022 ESC ventricular arrhythmia guideline had graded ICD therapy in symptomatic heart failure (NYHA class II–III) with LVEF ≤35% after ≥3 months of OMT Class I, Level A in CAD and Class IIa, Level A in dilated or hypokinetic non-dilated cardiomyopathy.^[5] ESC 2023 graded an ICD Class IIa, Level A in DCM or NDLVC with symptomatic heart failure and LVEF ≤35% despite >3 months of OMT.^[7] Those rows have no NYHA class or survival limit and are given in the partly-covered table above.^[7] The first two ESC 2026 rows above are for symptomatic HFrEF in NYHA class II/III.^[6] They do not cover the ESC 2022 CAD row for NYHA class I with LVEF ≤30% despite ≥3 months of OMT (Class IIa, Level B) in the primary-prevention table above.^[5][6] That row is given as current among the ESC guidelines checked for this topic.^[5]

Cardiac and inheritable conditions (selected rows from the ACC/AHA/HRS 2017 recommendation tables)

^[2]

ACC/AHA/HRS 2017 cautions that the baseline presence of an arrhythmia does not necessarily represent the cause of syncope, giving marked resting bradycardia in a young patient as an example.^[2] ACC/AHA/HRS 2017 supporting text notes that patients with aortic stenosis may experience syncope during exertion, often by a haemodynamic rather than arrhythmic mechanism.^[2]

Special populations

Older patients

Older patients (formal recommendation rows)

^{[1] [2] [4] [8]}

ESC 2018 applies the same assessment as for unexplained syncope to any unexplained fall (Class IIa, Level C).^[1] For recurrent unexplained falls, the ESC 2021 row above replaces it.^[1][4] For an unexplained fall that is not recurrent, no newer row was found in the ESC guidelines checked for this topic, so the ESC 2018 row is the newest.^[1][4]

ESC 2018 states that syncope may be unwitnessed in over half of older patients, which makes falls and syncope hard to tell apart.^[1] ESC 2018 adds that coincidental cardiovascular findings, such as aortic stenosis or AF, may not be the cause of events.^[1] ACC/AHA/HRS 2017 reports a 1-year fall rate of 38% among older fainters versus 18.3% among nonfainters.^[2]

Children and adolescents

ESC 2018 states that diagnostic evaluation in paediatric patients is similar to that in adults.^[1] ESC 2018 states that careful taking of personal and family history and a standard ECG are the most important methods of distinguishing benign reflex syncope (including reflex anoxic seizures or breath-holding spells) from other causes.^[1] ESC 2018 states that children with a history suggesting VVS, a normal ECG and no family history of arrhythmia should not undergo further cardiac investigations.^[1]

• ESC 2018, history that should prompt cardiac evaluation: family history of premature SCD at age <40 years and/or familial heart disease; known or suspected heart disease; triggers of loud noise, fright or extreme emotional stress; syncope during exercise, including swimming; syncope without prodromes, while supine or sleeping, or preceded by chest pain or palpitations.^[1]
• ESC 2018, pacing: even in VVS with prolonged asystole, pacemakers should be avoided in children because of the relatively transient and benign nature of the syndrome.^[1]

Paediatric syncope (selected rows from the ACC/AHA/HRS 2017 recommendation table)

^[2]

Psychogenic pseudosyncope

Psychogenic pseudosyncope (formal recommendation rows)

^{[1] [2]}

ESC 2018 advises that, in suspected PPS, tilt testing should preferably be done with EEG monitoring, where a normal EEG helps to confirm the diagnosis.^[1]

Driving

ACC/AHA/HRS 2017 states that it can be beneficial for healthcare providers to know the driving laws and restrictions in their regions and to discuss the implications with the patient (COR IIa, LOE C-EO).^[2] The ESC 2018 Web Practical Instructions advise first stratifying the clinical risk of the patient and the likely chance of a syncope recurrence.^[3]

Avoidance of private driving after an episode of syncope: suggested symptom-free waiting times (ACC/AHA/HRS 2017 Table 10)

^[2]

A footnote to the symptom-free waiting-time column of ACC/AHA/HRS 2017 Table 10 states that it may be prudent to wait and observe for the listed waiting time without a syncope spell before resuming driving.^[2] In ACC/AHA/HRS 2017 Table 10, RVOT and LVOT mean right and left ventricular outflow tract, and VF means ventricular fibrillation.^[2]

Advice for driving in patients with syncope (ESC 2018 Web Practical Instructions, Web Table 3)

^[3]

The ESC Web Practical Instructions define group 1 as private drivers of motorcycles, cars and other small vehicles with and without a trailer, and group 2 as professional drivers of vehicles over 3.5 tons or passenger vehicles with more than eight seats excluding the driver.^[3] The same document says taxicabs, small ambulances and other vehicles form an intermediate category that should follow local legislation, and that observation of therapy efficacy should generally be longer in group 2.^[3] The Web Practical Instructions report that recurrence of syncope during driving spans 3–9.8% among patients with a history of syncope, and that syncope-mediated car accidents occur at less than 1% per year.^[3]

Evidence, guidelines and regional differences

This topic follows the 2018 ESC syncope guideline, its Web Practical Instructions and the 2017 ACC/AHA/HRS syncope guideline; ESC grades rows by Class and Level, and ACC/AHA/HRS by COR and LOE.^[1][2] Where a newer ESC guideline checked for this topic (listed below) has a row on the same question, the topic gives the newest such row.^{[4][5][7][6][8]} Superseded ESC rows then appear only as dated history.^[4][5][7][6] For VT, catheter ablation and antiarrhythmic drugs follow a different rule.^[1] ESC 2018 cites, and refers detailed drug guidance in VT to, the 2015 ESC ventricular arrhythmia guideline, which ESC 2022 updates; the topic therefore gives the VT half of the ESC 2018 rows only as dated history.^[1][5] The topic gives selected ESC 2022 catheter ablation and AAD rows for treating VT in chronic CAD and in DCM/HNDCM, and the rows for patients with an ICD indication when an ICD is not available, contraindicated for concurrent medical reasons, or declined by the patient.^[5] For other VT substrates and settings (for example idiopathic VT, or the acute management of sustained VT), it names examples of the ESC tables that hold those rows but does not reproduce them.^[5][7] For SVT, no newer row on catheter ablation or drug therapy specific to syncope was found in the ESC guidelines checked for this topic.^[9] The topic therefore keeps the ESC 2018 rows for syncope due to SVT and gives examples of ESC 2019 rows for specific SVTs.^[1][9] Outside these ablation and drug rows, an older ESC row that a newer row covers only in part is still given, alongside the newer row or for the rest.^[4][1][8] Examples are suspected bradycardia, and BP-lowering medications in orthostatic hypotension with supine hypertension (including in older patients).^[4][1][8] Another is EPS after myocardial infarction or in other scar-related conditions.^[1][5] Others are the ESC 2018 ICD row for syncope with VT induced during EPS after myocardial infarction, and the ESC 2018 row on an ICD to reduce the risk of sudden death in unexplained syncope with systolic impairment.^[1][5][7] The same holds for the ESC 2018 ILR alternative to that ICD, and for the ESC 2022 DCM/HNDCM ICD row for LVEF <50% with ≥2 risk factors.^[1][5][7][6] So are the ESC 2023 DCM and NDLVC ICD rows for symptomatic heart failure with LVEF ≤35%.^[7][6] Another is the assessment of an unexplained fall that is not recurrent.^[1][4] The two bodies agree on the core: history, examination with orthostatic BP, and an ECG.^[1][2]

The 2021 ESC pacing guideline covers pacing and EPS in bradycardia, conduction disease and reflex syncope.^[4] The 2021 ESC pacing guideline also has rows on carotid sinus massage, ambulatory ECG monitoring, exercise testing, tilt testing, ILR and unexplained falls.^[4] The 2022 ESC ventricular arrhythmia guideline covers secondary-prevention ICD, PES and ICD in chronic CAD, and electrophysiological evaluation in DCM or HNDCM.^[5] It also covers catheter ablation and antiarrhythmic drugs for VT in chronic CAD and in DCM or HNDCM.^[5] The 2019 ESC SVT guideline has rows on catheter ablation and drug therapy for specific SVTs; the topic gives examples of them.^[9] The 2023 ESC cardiomyopathy guideline supplies the cardiomyopathy, DCM and NDLVC ICD rows given here.^[7] The 2026 ESC heart failure guideline supplies the primary- and secondary-prevention ICD rows in heart failure, including the row against primary-prevention ICD within 40 days of a myocardial infarction.^[6]

The 2024 ESC hypertension guideline supplies the rows on testing for orthostatic hypotension before starting or intensifying BP-lowering medication, and on BP-lowering drugs in orthostatic hypotension with supine hypertension.^[8] It also supplies the BP threshold and target rows for pre-treatment symptomatic orthostatic hypotension.^[8] The newer ESC guidelines checked for this topic are those on supraventricular tachycardia (2019), pulmonary embolism (2019), dyslipidaemias (2019 and 2025), adult congenital heart disease (2020), pacing (2021), ventricular arrhythmias (2022) and non-cardiac surgery (2022). The others checked are those on acute coronary syndromes, endocarditis and cardiomyopathies (2023), and on atrial fibrillation, chronic coronary syndromes, hypertension, and peripheral arterial and aortic diseases (2024). The last are those on valvular heart disease and pregnancy (2025), and on heart failure and cardiac rehabilitation (2026). For the 2020 sports cardiology guideline only the narrative text was checked, because its recommendation tables were not available as text. For the 2019 and 2025 dyslipidaemia documents, only the recommendation tables available as text were checked. The ESC guidelines on myocardial revascularisation (2018), cardiovascular disease prevention (2021), cardio-oncology (2022) and pulmonary hypertension (2022) were not checked. Nor were those on cardiovascular disease in diabetes (2023), myocarditis and pericarditis (2025), and cardiovascular disease in chronic kidney disease (2026). Statements in this topic that no newer ESC row was found refer to the checked guidelines only.

^{[1] [4] [2]}

ACC/AHA/HRS 2017 notes that the logistical and financial feasibility of specialised syncope units in North American settings is unknown.^[2] ESC 2018 states that tilt training has little efficacy in reducing recurrence of syncope in young patients with long-lasting recognisable prodromes, and ACC/AHA/HRS 2017 calls the usefulness of orthostatic training uncertain in patients with frequent VVS (COR IIb, LOE B-R).^[1][2]

Exam pearls

• ESC 2018 lists four features of TLOC: short duration, abnormal motor control, loss of responsiveness, and amnesia for the period of LOC.^[1]
• ESC 2018 Table 6 counts syncope during exertion or when supine as a major high-risk feature, but syncope in the sitting position as minor (high-risk only with structural heart disease or an abnormal ECG).^[1]
• ESC 2018 Table 7 lists injury caused by syncope among the features that favour admission in a patient with high-risk features.^[1]
• ESC 2018 states that the absence of arrhythmia during syncope excludes arrhythmic syncope.^[1]
• ESC 2018 states that CSM in carotid sinus syndrome usually shows a period of asystole >6 s.^[1]
• ESC 2018 states that EEG, neck artery ultrasound and brain CT or MRI are not indicated in patients with syncope (Class III, Level B), but in the same table recommends brain MRI if neurological examination indicates Parkinsonism, ataxia or cognitive impairment (Class I, Level C); ACC/AHA/HRS 2017 does not recommend routine EEG without specific neurological features suggestive of a seizure, or routine carotid imaging or head MRI and CT without focal neurological findings (or, for head imaging, head injury) that support further evaluation (each COR III: No Benefit).^[1][2]

References10ShowHide

1. [1]Brignole M, et al. 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J, 2018.PMID 29562304
2. [2]Shen WK, et al. 2017 ACC/AHA/HRS Guideline for the Evaluation and Management of Patients With Syncope: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. Circulation, 2017.PMID 28280231
3. [3]Brignole M, et al. Practical Instructions for the 2018 ESC Guidelines for the diagnosis and management of syncope. Eur Heart J, 2018.PMID 29562291
4. [4]Glikson M, et al. 2021 ESC Guidelines on cardiac pacing and cardiac resynchronization therapy. Eur Heart J, 2021.PMID 34455430
5. [5]Zeppenfeld K, et al. 2022 ESC Guidelines for the management of patients with ventricular arrhythmias and the prevention of sudden cardiac death. Eur Heart J, 2022.PMID 36017572
6. [6]Køber L, et al. 2026 ESC Guidelines for the management of heart failure. Eur Heart J, 2026.PMID 42661420
7. [7]Arbelo E, et al. 2023 ESC Guidelines for the management of cardiomyopathies. Eur Heart J, 2023.PMID 37622657
8. [8]McEvoy JW, et al. 2024 ESC Guidelines for the management of elevated blood pressure and hypertension. Eur Heart J, 2024.PMID 39210715
9. [9]Brugada J, et al. 2019 ESC Guidelines for the management of patients with supraventricular tachycardiaThe Task Force for the management of patients with supraventricular tachycardia of the European Society of Cardiology (ESC). Eur Heart J, 2020.PMID 31504425
10. [10]Baumgartner H, et al. 2020 ESC Guidelines for the management of adult congenital heart disease. Eur Heart J, 2021.PMID 32860028