Long QT, Brugada and inherited channelopathies — viva

Stem

Practice viva. The examiner works through patients referred to an inherited arrhythmia clinic. They are a child with exertional syncope and a normal resting ECG, a man with a very short QTc, a well young man with J-point elevation, the family of a young man who died suddenly, and a ward patient with torsades de pointes. Answer for non-pregnant patients.

Branch A — Exertional syncope with a normal resting ECG

Examiner: A 12-year-old girl faints while running. Her resting ECG and echocardiogram are normal. What diagnosis worries you, and how do you make it?^[1]

Strong answer:

• CPVT: ESC 2022 describes a heritable disorder with catecholamine-induced bidirectional and polymorphic VT in the absence of structural heart disease or ischaemia, whose manifestations usually occur in the first decade of life, prompted by physical activity or emotional stress.^[1]
• ESC 2022: most CPVT patients have a normal ECG and echocardiogram, and AHA/ACC/HRS 2017 notes that screening ECGs may be insufficient because the resting ECG in CPVT is normal.^[1][2]
• ESC 2022: the exercise stress test is the most important diagnostic test, because it elicits the distinguishing bidirectional or polymorphic VT; CPVT is diagnosed with a structurally normal heart, a normal ECG and exercise- or emotion-induced bidirectional or polymorphic VT (Class I, Level C).^[1]
• ESC 2022: genetic testing and genetic counselling are indicated with clinical suspicion or a clinical diagnosis of CPVT (Class I, Level C).^[1]

Follow-up: Her exercise test shows bidirectional VT. How do you treat her?^[1]

• ESC 2022: avoidance of competitive sports, strenuous exercise and exposure to stressful environments is recommended in all patients with CPVT (Class I, Level C).^[1]
• ESC 2022: beta-blockers, ideally non-selective (nadolol or propranolol), are recommended in all patients with a clinical diagnosis of CPVT (Class I, Level C).^[1]
• ESC 2022: flecainide should be considered with recurrent syncope, polymorphic or bidirectional VT, or persistent exertional PVCs on beta-blockers at the highest tolerated dose (Class IIa, Level C).^[1]
• ESC 2022: LCSD should be considered when beta-blockers plus flecainide at therapeutic dosage are not effective, not tolerated or contraindicated (Class IIa, Level C).^[1]

Follow-up: She later needs an ICD. What is special about programming it?^[1]

• ESC 2022: program long delays and high rates before defibrillation, because initiating bidirectional VT responds less effectively to defibrillation than subsequent polymorphic VT or VF, and painful shocks can trigger further and incessant arrhythmias.^[1]
• AHA/ACC/HRS 2017: inappropriate shocks are reported in 20% to 30% of CPVT patients with ICDs, and programming should be optimised to deliver therapy for VF and to minimise inappropriate shocks and the risk of potentially fatal electrical storms.^[2]

Follow-up: At 16 she wants to return to competitive running. How do the European and US documents differ?^[1][10]

• ESC 2022 recommends avoidance of competitive sports, strenuous exercise and exposure to stressful environments in all patients with CPVT (Class I, Level C).^[1]
• AHA/ACC 2025 (Table 13): in competitive athletes with previously symptomatic CPVT for whom competitive sport is being considered, combination therapy with a beta-blocker and flecainide, and possibly LCSD, is required before competitive sport is resumed, and these therapies should be optimised with normalisation of the stress test first.^[10]
• AHA/ACC 2025: she should be assessed by a paediatric or adult cardiologist with expertise in cardiac channelopathies, with shared decision-making.^[10]

Branch B — A very short QTc

Examiner: A 30-year-old man survived a VF arrest. His heart is structurally normal and his QTc is 330 ms. What is the diagnosis and the plan?^[1]

Strong answer:

• ESC 2022 diagnoses SQTS with a QTc of 360 ms or less and one or more of a pathogenic mutation, a family history of SQTS, or survival from a VT/VF episode in the absence of heart disease (Class I, Level C); he meets the third criterion.^[1]
• ESC 2022: ICD implantation is recommended in SQTS patients who are survivors of an aborted cardiac arrest and/or have documented spontaneous sustained VT (Class I, Level C), and genetic testing is recommended in patients diagnosed with SQTS (Class I, Level C).^[1]
• AHA/ACC/HRS 2017: in SQTS with cardiac arrest or sustained VA, an ICD is recommended if meaningful survival greater than 1 year is expected (COR I, LOE B-NR).^[2]
• ESC 2022: drugs that shorten the QT interval, such as nicorandil, should be avoided.^[1]

Follow-up: What drug has a role?^[1]

• ESC 2022: quinidine is currently the best supported antiarrhythmic drug but should be monitored for excessive QT prolongation; quinidine may be considered in SQTS patients who qualify for an ICD but have a contraindication or refuse it, and in asymptomatic SQTS patients with a family history of SCD (Class IIb, Level C).^[1]
• AHA/ACC/HRS 2017: in SQTS with recurrent sustained VA, treatment with quinidine can be useful (COR IIa, LOE C-LD).^[2]

Branch C — J-point elevation in a well young man

Examiner: An asymptomatic 20-year-old man has 1 mm J-point elevation in two adjacent inferior leads on an ECG recorded before minor surgery. What do you call it and what do you do?^[1]

Strong answer:

• ESC 2022 diagnoses the early repolarization pattern as J-point elevation of 1 mm or more in two adjacent inferior and/or lateral ECG leads (Class I, Level C); it is most often a benign finding, reported in 5.8% of adults and more common in young males and athletes.^[1]
• ESC 2022: clinical evaluation is not recommended routinely in asymptomatic subjects with ERP (Class III, Level C); AHA/ACC/HRS 2017: observation without treatment is recommended (COR I, LOE B-NR).^[1][2]
• AHA/ACC/HRS 2017: genetic testing is not recommended in patients with an early repolarization pattern (COR III: No Benefit, LOE B-NR).^[2]

Follow-up: When does the pattern become a syndrome?^[1]

• ESC 2022: ERS is diagnosed in a patient resuscitated from unexplained VF or polymorphic VT in the presence of ERP (Class I, Level C).^[1]
• ESC 2022 lists proposed high-risk ECG features: prominent J waves of 2 mm or more, dynamic changes in J-point elevation above 0.1 mV, and J waves with a horizontal or descending ST segment.^[1]
• ESC 2022: ICD implantation is recommended in ERS patients who have survived a cardiac arrest (Class I, Level B), and quinidine in addition to an ICD should be considered for recurrent VF in ERS (Class IIa, Level B).^[1]

Branch D — The family of a young man who died suddenly

Examiner: A 26-year-old man died suddenly. What should happen to the decedent?^[1]

Strong answer:

• ESC 2022: a comprehensive autopsy is recommended, ideally in all cases of unexpected sudden death and always below 50 years of age (Class I, Level B).^[1]
• ESC 2022: retain samples suitable for DNA extraction and consult a cardiac pathologist when an inherited cause is suspected or the cause of death is unexplained (Class I, Level B).^[1]
• ESC 2022: after SADS, post-mortem genetic testing targeted to primary electrical disease is recommended when the decedent is young (below 50) and/or the circumstances and/or family history support a primary electrical disease (Class I, Level B); hypothesis-free exome or genome sequencing is not recommended (Class III, Level B).^[1]

Follow-up: The autopsy is negative. How do you assess his family?^[1]

• ESC 2022 recommends familial evaluation of SADS decedents for first-degree relatives, relatives who must carry a mutation based on the family history, relatives with suspicious symptoms, and when the decedent was below 50 years or other circumstantial data or family history suggest heritable disease (Class I, Level B).^[1]
• The baseline evaluation includes a medical history, physical examination, standard and high precordial lead ECG, echocardiography and exercise testing (Class I, Level B).^[1]
• ESC 2022: in SADS families without a diagnosis after clinical evaluation, follow-up is recommended for children of decedents until they reach adulthood (Class I, Level C), whereas follow-up is not recommended for asymptomatic adults, who can be discharged with advice to return if they develop symptoms or the family history changes (Class III, Level C).^[1]
• ESC 2022 reports a diagnostic yield of 18 to 53% in families of SADS decedents, with LQTS, BrS, CPVT and cardiomyopathy among the causes.^[1]

Branch E — Torsades de pointes on the ward

Examiner: A ward patient on several new drugs has recurrent torsades de pointes with a long QT. What do you do?^[1]

Strong answer:

• ESC 2022: suspect drug-induced arrhythmia in patients on agents that alter the electrical properties of the heart or cause electrolyte abnormalities; withdrawal of offending agents is recommended whenever drug-induced VAs are suspected (Class I, Level B).^[1]
• AHA/ACC/HRS 2017: with QT prolongation due to a medication, hypokalaemia, hypomagnesaemia or another acquired factor and recurrent torsades de pointes, intravenous magnesium sulfate is recommended to suppress the arrhythmia (COR I, LOE C-LD), and potassium repletion to 4.0 mmol/L or more and magnesium repletion to normal values are beneficial (COR I, LOE C-LD).^[2]
• ESC 2022: intravenous magnesium is an effective therapy for TdP even in the absence of hypomagnesaemia.^[1]

Follow-up: The torsades continues despite magnesium and she is bradycardic.^[2]

• AHA/ACC/HRS 2017: with recurrent torsades associated with acquired QT prolongation and bradycardia that cannot be suppressed with intravenous magnesium, increasing the heart rate with atrial or ventricular pacing or isoproterenol is recommended (COR I, LOE B-NR).^[2]
• ESC 2022: in refractory recurrent TdP in the setting of acquired long QT, the arrhythmia can be suppressed by increasing the heart rate with isoproterenol (isoprenaline) or transvenous pacing.^[1]