Cardioversion and anticoagulation timing — structured viva

Abbreviations

Stem

Practice viva. You are the cardiology registrar. The examiner asks you to defend decisions about cardioversion of AF: the unstable patient, the duration thresholds, imaging, the anticoagulant, the technique and the drug. Name the body and year with each recommendation.

Branch A — The unstable patient

Examiner: AF at 150 beats per minute, blood pressure 78/40 mmHg, and the patient is clammy. What do you do?

Strong answer:

• ESC 2024 recommends electrical cardioversion in AF patients with acute or worsening haemodynamic instability, to improve immediate patient outcomes (Class I, Level C), and its text recommends rapid electrical cardioversion when the instability is thought to be caused by AF; ACC/AHA 2023 says immediate electrical cardioversion should be performed to restore sinus rhythm when instability is attributable to AF (COR 1, LOE C-LD).^[1][2]
• Initiation of therapeutic anticoagulation should be considered as soon as possible in this unscheduled cardioversion, to prevent procedure-related thromboembolism (ESC 2024, Class IIa, Level B); afterwards, OAC is recommended for at least 4 weeks in all patients after cardioversion and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (ESC 2024, Class I, Level B).^[1]
• Synchronise: energy delivery should be confirmed to be synchronised to the QRS to reduce the risk of inducing VF (ACC/AHA 2023, COR 1, LOE C-LD).^[2]
• The ACC/AHA anticoagulation row covers patients with AF undergoing cardioversion: therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR).^[2]

Follow-up: What if the instability came from sepsis, with AF as a bystander?^[1]

• The ESC counts severely ill patients who develop AF (for example with sepsis) among unstable patients, and says spontaneous restoration of sinus rhythm has been reported in up to 83% during the first 48 h after appropriate treatment of the underlying cause.^[1]
• The ESC still considers emergency electrical cardioversion the first-choice treatment if sinus rhythm is thought to be beneficial, despite a high rate of immediate relapse; amiodarone is a second-line option because of its delayed activity, although it may be an appropriate alternative in the acute setting. The ESC 2024 row wording has no cause clause: electrical cardioversion is recommended in AF patients with acute or worsening haemodynamic instability, to improve immediate patient outcomes (Class I, Level C), although the ESC text frames rapid electrical cardioversion for instability thought to be caused by AF. The ACC/AHA immediate-cardioversion row is for instability attributable to AF (COR 1, LOE C-LD).^[1][2]
• If the patient is cardioverted (electrically, or pharmacologically, for example with amiodarone), the cardioversion anticoagulation rows from the main answer still cover the patient: ESC 2024 says initiation of therapeutic anticoagulation should be considered as soon as possible in unscheduled cardioversion, to prevent procedure-related thromboembolism (Class IIa, Level B), and OAC is recommended for at least 4 weeks in all patients after cardioversion and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B); ACC/AHA 2023 says therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR).^[1][2]
• Anticoagulation for stroke prevention during the septic illness is less certain, and the longer-term decision follows it. ACC/AHA 2023: in patients with AF identified in the setting of critical illness due to sepsis, the benefits of anticoagulation during critical illness for stroke prevention are uncertain (COR 2b, LOE B-NR); in patients with AF identified in the setting of acute medical illness or surgery, outpatient follow-up for thromboembolic risk stratification and decision-making on OAC initiation or continuation, as well as AF surveillance, can be beneficial given a high risk of AF recurrence (COR 2a, LOE B-NR). ESC 2024 names acute sepsis as the most common precipitant unmasking a tendency to AF and says that in the acute phase of sepsis, patients show an unclear risk–benefit profile with anticoagulation therapy; its row says long-term oral anticoagulation should be considered in suitable patients with trigger-induced AF at elevated thromboembolic risk, to prevent ischaemic stroke and systemic thromboembolism (Class IIa, Level C), and its text places the start of OAC after the acute trigger has been corrected.^[2][1]

Branch B — Duration thresholds

Examiner: A stable patient has had AF for 30 hours. Can you cardiovert today without anticoagulation or imaging?

Strong answer:

• Under ESC 2024, no: early cardioversion is not recommended without appropriate anticoagulation or TOE if AF has lasted longer than 24 h, or if there is scope to wait for spontaneous cardioversion (Class III, Level C). At 30 hours and stable, the patient is still within 48 h of onset, and a wait-and-see approach for spontaneous conversion to sinus rhythm within 48 h of AF onset should be considered in patients without haemodynamic compromise as an alternative to immediate cardioversion (Class IIa, Level B); if cardioversion can be scheduled, therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) is recommended first, to prevent procedure-related thromboembolism (Class I, Level B); DOACs are recommended in preference to VKAs in eligible patients with AF undergoing cardioversion, for thromboembolic risk reduction (Class I, Level A).^[1]
• If cardioversion cannot wait, initiation of therapeutic anticoagulation should be considered as soon as possible in unscheduled cardioversion, to prevent procedure-related thromboembolism (Class IIa, Level B); because the AF has lasted 24 h or more, the route is TOE-guided cardioversion, as TOE is recommended if 3 weeks of therapeutic OAC has not been provided, for exclusion of cardiac thrombus to enable early cardioversion (Class I, Level B).^[1]
• The ESC explains that the definite onset of AF is often not known, observational data suggest stroke or thromboembolism risk is lowest within a much shorter time period, and the task force reached consensus that safety should come first.^[1]
• After cardioversion, ESC 2024 recommends OAC for at least 4 weeks in all patients and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B).^[1]
• Under ACC/AHA 2023, not without anticoagulation either: in patients with AF undergoing cardioversion, therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR).^[2]
• ACC/AHA 2023 uses 48 hours for imaging: with a reported AF duration under 48 hours, without anticoagulation and not in the setting of cardiac surgery, pre-cardioversion imaging to exclude intracardiac thrombus may be considered in those at elevated thromboembolic risk (CHA2DS2-VASc 2 or more or equivalent) (COR 2b, LOE C-LD).^[2]

Follow-up: Is anyone low enough risk to skip imaging and anticoagulation altogether?^[2]

• ACC/AHA 2023: in patients with AF undergoing cardioversion, therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR). For the lowest-risk group a separate row says that with CHA2DS2-VASc 0–1 or equivalent and AF under 12 hours, the benefit of pre-cardioversion imaging or peri-cardioversion anticoagulation is uncertain, given the low incidence of peri-cardioversion thromboembolic events (COR 2b, LOE C-LD).^[2]
• The ACC/AHA cites retrospective FinCV (Finnish CardioVersion) data, from cardioversion of acute AF (AF lasting under 48 h), showing 30-day peri-cardioversion thromboembolic event rates of 0.4% with CHA2DS2-VASc 0 to 1 and 0.3% with AF under 12 hours.^[2][11]
• ESC 2024 Recommendation Table 15 has no equivalent low-risk row. Early cardioversion is not recommended without appropriate anticoagulation or TOE if AF duration is longer than 24 h, or there is scope to wait for spontaneous cardioversion (Class III, Level C); a wait-and-see approach for spontaneous conversion within 48 h of AF onset should be considered in patients without haemodynamic compromise, as an alternative to immediate cardioversion (Class IIa, Level B); and if cardioversion goes ahead unscheduled, initiation of therapeutic anticoagulation should be considered as soon as possible, to prevent procedure-related thromboembolism (Class IIa, Level B).^[1]
• After cardioversion, ESC 2024 recommends OAC for at least 4 weeks in all patients and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B); the ESC text makes post-cardioversion OAC optional only for patients without thromboembolic risk factors whose sinus rhythm was restored within 24 h of AF onset.^[1]

Branch C — Imaging and thrombus

Examiner: How does imaging change the timing?

Strong answer:

• ESC 2024 before cardioversion: therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) is recommended before scheduled cardioversion, to prevent procedure-related thromboembolism (Class I, Level B); TOE is recommended if 3 weeks of therapeutic OAC has not been provided, for exclusion of cardiac thrombus to enable early cardioversion (Class I, Level B); early cardioversion is not recommended without appropriate anticoagulation or TOE if AF duration is longer than 24 h, or there is scope to wait for spontaneous cardioversion (Class III, Level C).^[1]
• In the ESC 2024 flowchart (Figure 12), a stable patient already on therapeutic OAC for at least 3 weeks goes to pharmacological or electrical cardioversion (Class IIa) or a wait-and-see approach for spontaneous conversion (Class IIa; Rec Table 15: within 48 h of AF onset, in patients without haemodynamic compromise, as an alternative to immediate cardioversion, Class IIa, Level B). A stable patient not already on OAC who is suitable for wait-and-see (Class IIa) has therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) before scheduled cardioversion (Class I), then elective electrical cardioversion if needed; if cardioversion cannot wait, initiation of a DOAC (or VKA, LMWH or UFH) as soon as possible should be considered for unscheduled cardioversion, to prevent procedure-related thromboembolism (Class IIa; Rec Table 15: Class IIa, Level B), the current AF episode duration is checked, and AF onset under 24 h leads to pharmacological or electrical cardioversion, while onset of 24 h or more or unknown leads to TOE-guided cardioversion (Class I). DOACs are recommended in preference to VKAs in eligible patients with AF undergoing cardioversion, for thromboembolic risk reduction (Class I, Level A).^[1]
• ESC 2024 after cardioversion: OAC is recommended for at least 4 weeks in all patients and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B); the flowchart gives short-term OAC (4 weeks) for all patients, even if CHA2DS2-VA = 0, optional if AF onset is definitely under 24 h and thromboembolic risk is low, and the ESC text makes it optional only without thromboembolic risk factors and with sinus rhythm restored within 24 h of AF onset.^[1]
• ACC/AHA 2023: therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR); with AF of 48 hours or more, a 3-week duration of uninterrupted therapeutic anticoagulation or imaging evaluation to exclude intracardiac thrombus is recommended before elective cardioversion (COR 1, LOE B-R).^[2]
• ACC/AHA 2023, below 48 hours: with a reported AF duration under 48 hours (not in the setting of cardiac surgery) and no anticoagulation, pre-cardioversion imaging to exclude intracardiac thrombus may be considered in those at elevated thromboembolic risk (CHA2DS2-VASc 2 or more or equivalent) (COR 2b, LOE C-LD); with low thromboembolic risk (CHA2DS2-VASc 0–1 or equivalent) and AF under 12 hours, the benefit of pre-cardioversion imaging or peri-cardioversion anticoagulation is uncertain, given the low incidence of peri-cardioversion thromboembolic events in this population (COR 2b, LOE C-LD).^[2]
• ACC/AHA text: cardiac computed tomography, particularly with a delayed contrast-enhanced acquisition protocol, has emerged as an alternate imaging modality to exclude intracardiac thrombus.^[2]
• In ACUTE (1222 patients with AF of more than two days), TEE-guided management showed no significant difference in embolic events within eight weeks vs conventional warfarin for 3 weeks before electrical cardioversion (0.8% vs 0.5%; P = 0.50), fewer haemorrhagic events (2.9% vs 5.5%) and a shorter time to cardioversion (3.0 vs 30.6 days).^[10][2]

Follow-up: The TOE shows LAA thrombus. Now what?^[2]

• ESC 2024: therapeutic anticoagulation for a minimum of 4 weeks, followed by repeat TOE to ensure thrombus resolution (text); repeat TOE before cardioversion should be considered (Class IIa, Level C).^[1]
• ACC/AHA 2023: cancel the planned cardioversion; therapeutic anticoagulation should be instituted for at least 3 to 6 weeks, after which imaging should be repeated before cardioversion (COR 1, LOE C-LD); if the patient was already anticoagulated, assess compliance, dosing appropriateness, drug absorption and drug interactions.^[2]

Branch D — Which anticoagulant, and for how long?

Examiner: Warfarin or a DOAC for cardioversion?

Strong answer:

• ESC 2024: DOACs are recommended in preference to VKAs in eligible patients with AF undergoing cardioversion, for thromboembolic risk reduction (Class I, Level A).^[1]
• ACC/AHA 2023: its section 8.2.1 cardioversion text says DOACs are alternatives to VKAs as thromboprophylaxis in the setting of cardioversion and, given rapid time to therapeutic efficacy, reliability of maintenance of therapeutic efficacy and ease of continuation, may be preferentially considered over VKAs for patients with AF planned for cardioversion, barring contraindications to DOAC therapy; its general antithrombotic row says that in patients with AF who do not have a history of moderate to severe rheumatic mitral stenosis or a mechanical heart valve, and who are candidates for anticoagulation, DOACs are recommended over warfarin to reduce the risk of mortality, stroke, systemic embolism and intracranial haemorrhage (COR 1, LOE A).^[2]
• The ESC cites a meta-analysis of 5203 patients from three underpowered trials, predominantly undergoing electrical cardioversion, in which the composite of stroke, systemic embolism, MI and cardiovascular death was significantly lower with DOACs than with VKAs (0.42% vs 0.98%), with no significant difference in major bleeding.^[1]
• X-VeRT (rivaroxaban vs VKA, 1504 patients with AF undergoing elective cardioversion): primary efficacy composite 0.51% vs 1.02% (risk ratio 0.50; 95% CI 0.15–1.73), with a significantly shorter time to cardioversion on rivaroxaban.^[7]

Follow-up: How long after cardioversion?^[1]

• ESC 2024: OAC is recommended for at least 4 weeks in all patients, and long-term in patients with thromboembolic risk factor(s) irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B); ACC/AHA 2023: therapeutic anticoagulation should be established before and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR).^[1][2]
• The ACC/AHA bases this on elevated thromboembolic risk, especially within the 30 days after cardioversion, high early recurrence of AF and atrial dysfunction, with recovery of mechanical atrial systole over the ensuing month.^[2]

Branch E — Choosing the drug

Examiner: Recent-onset AF, stable, and the patient wants a drug. How do you choose?

Strong answer:

• ESC 2024 bases the choice on the type and severity of concomitant heart disease: intravenous flecainide or propafenone is recommended when pharmacological cardioversion of recent-onset AF is desired, excluding severe LVH, HFrEF or coronary artery disease; intravenous vernakalant is recommended in the same situation, excluding recent ACS, HFrEF or severe aortic stenosis; intravenous amiodarone is recommended when cardioversion is desired in severe LVH, HFrEF or coronary artery disease, accepting there may be a delay in cardioversion (all Class I, Level A).^[1]
• Pharmacological cardioversion is not recommended in sinus node dysfunction, atrioventricular conduction disturbances or prolonged QTc (above 500 ms), unless risks for proarrhythmia and bradycardia have been considered (ESC 2024, Class III, Level C).^[1]
• ACC/AHA 2023: pharmacological cardioversion is reasonable as an alternative to electrical cardioversion in those who are haemodynamically stable, or when electrical cardioversion is preferred but cannot be performed (COR 2a, LOE C-LD); ibutilide is reasonable without depressed LV function (LVEF under 40%) (COR 2a, LOE A); intravenous amiodarone is reasonable, although time to conversion is generally longer than with other agents (8–12 hours) (COR 2a, LOE A); intravenous procainamide may be considered when other intravenous agents are contraindicated or not preferred (COR 2b, LOE B-R).^[2]
• Anticoagulation still applies. ESC 2024 text: anticoagulation should be started or continued according to a formal (re-)assessment of thromboembolic risk. ACC/AHA 2023 text: thromboembolic risks and considerations of anticoagulation apply to both pharmacological and electrical cardioversion.^[1][2]
• ESC 2024 before cardioversion: therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) is recommended before scheduled cardioversion, to prevent procedure-related thromboembolism (Class I, Level B); TOE is recommended if 3 weeks of therapeutic OAC has not been provided, for exclusion of cardiac thrombus to enable early cardioversion (Class I, Level B); early cardioversion is not recommended without appropriate anticoagulation or TOE if AF duration is longer than 24 h, or there is scope to wait for spontaneous cardioversion (Class III, Level C).^[1]
• In the ESC 2024 flowchart (Figure 12), a stable patient already on therapeutic OAC for at least 3 weeks goes to pharmacological or electrical cardioversion (Class IIa) or a wait-and-see approach for spontaneous conversion (Class IIa; Rec Table 15: within 48 h of AF onset, in patients without haemodynamic compromise, as an alternative to immediate cardioversion, Class IIa, Level B). A stable patient not already on OAC who is suitable for wait-and-see (Class IIa) has therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) before scheduled cardioversion (Class I), then elective electrical cardioversion if needed; if cardioversion cannot wait, initiation of a DOAC (or VKA, LMWH or UFH) as soon as possible should be considered for unscheduled cardioversion, to prevent procedure-related thromboembolism (Class IIa; Rec Table 15: Class IIa, Level B), the current AF episode duration is checked, and AF onset under 24 h leads to pharmacological or electrical cardioversion, while onset of 24 h or more or unknown leads to TOE-guided cardioversion (Class I). DOACs are recommended in preference to VKAs in eligible patients with AF undergoing cardioversion, for thromboembolic risk reduction (Class I, Level A).^[1]
• ESC 2024 after cardioversion: OAC is recommended for at least 4 weeks in all patients and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B); the flowchart gives short-term OAC (4 weeks) for all patients, even if CHA2DS2-VA = 0, optional if AF onset is definitely under 24 h and thromboembolic risk is low, and the ESC text makes it optional only without thromboembolic risk factors and with sinus rhythm restored within 24 h of AF onset.^[1]
• ACC/AHA 2023: therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR); with AF of 48 hours or more, a 3-week duration of uninterrupted therapeutic anticoagulation or imaging evaluation to exclude intracardiac thrombus is recommended before elective cardioversion (COR 1, LOE B-R).^[2]
• ACC/AHA 2023, below 48 hours: with a reported AF duration under 48 hours (not in the setting of cardiac surgery) and no anticoagulation, pre-cardioversion imaging to exclude intracardiac thrombus may be considered in those at elevated thromboembolic risk (CHA2DS2-VASc 2 or more or equivalent) (COR 2b, LOE C-LD); with low thromboembolic risk (CHA2DS2-VASc 0–1 or equivalent) and AF under 12 hours, the benefit of pre-cardioversion imaging or peri-cardioversion anticoagulation is uncertain, given the low incidence of peri-cardioversion thromboembolic events in this population (COR 2b, LOE C-LD).^[2]

Follow-up: Why does LVEF matter for ibutilide?^[2]

• The ACC/AHA says torsades de pointes with ibutilide is more frequent with reduced LVEF, so ibutilide is best avoided with LVEF 40% or less, and that magnesium immediately before ibutilide may mitigate the risk of torsades and excessive QT prolongation.^[2]

Branch F — Electrical technique

Examiner: Walk me through an elective electrical cardioversion.

Strong answer:

• Anticoagulation comes first: ESC 2024 recommends therapeutic OAC before scheduled cardioversion, to prevent procedure-related thromboembolism, and ACC/AHA 2023 says therapeutic anticoagulation should be established before cardioversion, to prevent thromboembolism.^[1][2]
• ESC 2024 before cardioversion: therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) is recommended before scheduled cardioversion, to prevent procedure-related thromboembolism (Class I, Level B); TOE is recommended if 3 weeks of therapeutic OAC has not been provided, for exclusion of cardiac thrombus to enable early cardioversion (Class I, Level B); early cardioversion is not recommended without appropriate anticoagulation or TOE if AF duration is longer than 24 h, or there is scope to wait for spontaneous cardioversion (Class III, Level C).^[1]
• In the ESC 2024 flowchart (Figure 12), a stable patient already on therapeutic OAC for at least 3 weeks goes to pharmacological or electrical cardioversion (Class IIa) or a wait-and-see approach for spontaneous conversion (Class IIa; Rec Table 15: within 48 h of AF onset, in patients without haemodynamic compromise, as an alternative to immediate cardioversion, Class IIa, Level B). A stable patient not already on OAC who is suitable for wait-and-see (Class IIa) has therapeutic OAC for at least 3 weeks (adherence to DOACs or INR 2.0 or more for VKAs) before scheduled cardioversion (Class I), then elective electrical cardioversion if needed; if cardioversion cannot wait, initiation of a DOAC (or VKA, LMWH or UFH) as soon as possible should be considered for unscheduled cardioversion, to prevent procedure-related thromboembolism (Class IIa; Rec Table 15: Class IIa, Level B), the current AF episode duration is checked, and AF onset under 24 h leads to pharmacological or electrical cardioversion, while onset of 24 h or more or unknown leads to TOE-guided cardioversion (Class I). DOACs are recommended in preference to VKAs in eligible patients with AF undergoing cardioversion, for thromboembolic risk reduction (Class I, Level A).^[1]
• ESC 2024 after cardioversion: OAC is recommended for at least 4 weeks in all patients and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B); the flowchart gives short-term OAC (4 weeks) for all patients, even if CHA2DS2-VA = 0, optional if AF onset is definitely under 24 h and thromboembolic risk is low, and the ESC text makes it optional only without thromboembolic risk factors and with sinus rhythm restored within 24 h of AF onset.^[1]
• ACC/AHA 2023: therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR); with AF of 48 hours or more, a 3-week duration of uninterrupted therapeutic anticoagulation or imaging evaluation to exclude intracardiac thrombus is recommended before elective cardioversion (COR 1, LOE B-R).^[2]
• ACC/AHA 2023, below 48 hours: with a reported AF duration under 48 hours (not in the setting of cardiac surgery) and no anticoagulation, pre-cardioversion imaging to exclude intracardiac thrombus may be considered in those at elevated thromboembolic risk (CHA2DS2-VASc 2 or more or equivalent) (COR 2b, LOE C-LD); with low thromboembolic risk (CHA2DS2-VASc 0–1 or equivalent) and AF under 12 hours, the benefit of pre-cardioversion imaging or peri-cardioversion anticoagulation is uncertain, given the low incidence of peri-cardioversion thromboembolic events in this population (COR 2b, LOE C-LD).^[2]
• ACC/AHA 2023: in haemodynamically stable AF, electrical cardioversion can be performed as the initial rhythm-control strategy or after unsuccessful pharmacological cardioversion (COR 1, LOE B-R).^[2]
• Sedation with intravenous midazolam, propofol or etomidate; blood pressure monitoring and oximetry; atropine, isoproterenol or transcutaneous pacing available for post-cardioversion bradycardia (ESC 2024 text).^[1]
• Energy delivery should be confirmed to be synchronised to the QRS, to reduce the risk of inducing VF (ACC/AHA 2023, COR 1, LOE C-LD), with synchronisation confirmed before each shock attempt.^[2]
• For elective electrical cardioversion, biphasic energy of at least 200 J as initial energy can be beneficial to improve success of the initial shock (ACC/AHA 2023, COR 2a, LOE B-R); in a single-centre randomised trial of 276 patients with AF having elective cardioversion, maximum-fixed (360-360-360 J) biphasic shocks gave sinus rhythm at 1 min in 88% vs 66% with low-escalating (125-150-200 J) shocks, with no significant difference in any safety endpoint.^[2][15]

Follow-up: The first shock fails. What next?^[2]

• ACC/AHA 2023: in elective cardioversion with longer AF or an unsuccessful initial shock, optimising the electrode vector, higher energy and pretreatment with antiarrhythmic drugs can facilitate success (COR 2a, LOE B-NR); in obesity, manual pressure augmentation and/or further escalation of electrical energy may be beneficial to improve success of electrical cardioversion (COR 2b, LOE C-LD).^[2]
• The ESC says 3–4 days of pretreatment with flecainide, ibutilide, propafenone or amiodarone, or immediate vernakalant, improves the rate of successful ECV.^[1]

Branch G — Special situations

Examiner: She is 28 weeks pregnant and unstable in AF. Does pregnancy change the shock?

Strong answer:

• ESC 2024 recommends electrical cardioversion in AF patients with acute or worsening haemodynamic instability, to improve immediate patient outcomes (Class I, Level C), and, in pregnancy, immediate electrical cardioversion in AF with haemodynamic instability or pre-excited AF, to improve maternal and foetal outcomes (Class I, Level C). The 2025 ESC pregnancy guideline recommends immediate electrical cardioversion for acute treatment of SVT with haemodynamic instability (Class I, Level C), and its text says that with haemodynamic instability caused by any SVT, including AF and AFL, synchronised direct current cardioversion is indicated.^[1][4]
• The 2025 ESC pregnancy guideline says transthoracic impedance does not change in pregnancy, so shock energies should be the same as outside pregnancy, with foetal heart rate monitoring after cardioversion.^[4]
• ACC/AHA 2023: with haemodynamic instability attributable to AF, immediate electrical cardioversion should be performed to restore sinus rhythm (COR 1, LOE C-LD); in pregnant patients with AF, DC cardioversion is safe to the patient and fetus and should be performed in the same manner as in patients who are not pregnant (COR 1, LOE B-NR); energy delivery should be confirmed to be synchronised to the QRS to reduce the risk of inducing VF (COR 1, LOE C-LD).^[2]
• Anticoagulation, ESC: the 2025 ESC pregnancy guideline says the indication for anticoagulation with LMWH before cardioversion, or the need for TOE, should be evaluated as in non-pregnant women, and anticoagulation maintained for at least 4 weeks after cardioversion. As in non-pregnant patients, ESC 2024 says initiation of therapeutic anticoagulation should be considered as soon as possible in unscheduled cardioversion, to prevent procedure-related thromboembolism (Class IIa, Level B), and OAC is recommended for at least 4 weeks in all patients after cardioversion and long-term in patients with thromboembolic risk factor(s), irrespective of whether sinus rhythm is achieved, to prevent thromboembolism (Class I, Level B).^[4][1]
• The ESC pregnancy anticoagulation rows differ by guideline: ESC 2024 AF recommends therapeutic anticoagulation with LMWHs or VKAs (except VKAs in the first trimester or beyond week 36) for pregnant patients with AF at elevated thromboembolic risk, to prevent ischaemic stroke and thromboembolism (Class I, Level C); under long-term management of SVT and AF, the newer ESC 2025 pregnancy guideline recommends therapeutic anticoagulation with LMWH for pregnant women with persistent or permanent AF at elevated thromboembolic risk (Class I, Level C). On the agent, the ESC 2025 pregnancy guideline says DOACs are not recommended during pregnancy (Class III, Level C), and ESC 2024 text says the same because of safety concerns.^[1][4]
• Anticoagulation, ACC/AHA: for patients with AF undergoing cardioversion, therapeutic anticoagulation should be established before cardioversion and continued for at least 4 weeks afterwards without interruption, to prevent thromboembolism (COR 1, LOE B-NR); its pregnancy row says pregnant individuals with AF and elevated risk of stroke may be considered for anticoagulation, recognising that no anticoagulation strategy is completely safe for both mother and fetus, and that a shared decision-making discussion should take place regarding the risks to both (COR 2b, LOE C-LD).^[2]

Follow-up: And a patient with an LAA occlusion device, off anticoagulation?^[2]

• ACC/AHA 2023: imaging to assess the adequacy of LAAO and exclude device-related thrombosis before cardioversion may be reasonable (COR 2b, LOE B-NR); with a residual leak, peri-cardioversion anticoagulation may be considered and continued thereafter (COR 2b, LOE C-LD).^[2]
• In cardiac amyloidosis, the 2026 ESC heart failure guideline says TOE is necessary before cardioversion to exclude intracardiac thrombus, regardless of the duration of anticoagulation before the procedure.^[3]