Long QT, Brugada and inherited channelopathies — structured written assessment

SAQ 1 (10 marks)

Practice scenario. A 16-year-old girl fainted when she was startled by a loud alarm. Repeated 12-lead ECGs show a QTc of 490 ms. Her heart is structurally normal, and she takes no QT-prolonging drugs.^[1]

1. Give the ESC 2022 routes to a diagnosis of LQTS, with class and level. (2)^[1]
2. Which LQTS genotype fits her trigger, and what are the three undisputed LQTS genes? (2)^[1]
3. What general measures and first-line drug treatment do ESC 2022 and AHA/ACC/HRS 2017 recommend? (2)^[1][2]
4. List the high-risk features of LQTS given by AHA/ACC/HRS 2017. (2)^[2]
5. Despite a beta-blocker she has a further arrhythmic syncope. What do the ESC 2022 rows on ICD and LCSD say? (2)^[1]

Model answers — SAQ 1

1. ESC 2022: LQTS is diagnosed with either a QTc of 480 ms or more in repeated 12-lead ECGs, with or without symptoms, or an LQTS diagnostic score above 3 (Class I, Level C) (half a mark); it is also diagnosed in the presence of a pathogenic mutation, irrespective of the QT duration (Class I, Level C) (half a mark).^[1] The diagnosis should be considered with a QTc of 460 ms or more and below 480 ms in repeated 12-lead ECGs in a patient with an arrhythmic syncope, in the absence of secondary causes for QT prolongation (Class IIa, Level C) (1 mark).^[1]
2. ESC 2022 names emotional stress as the gene-specific trigger for LQT2, and exposure to loud noises as the LQT2 trigger to avoid, so her history fits LQT2 (1 mark).^[1] The undisputed genes are KCNQ1 (LQT1), KCNH2 (LQT2) and SCN5A (LQT3) (1 mark).^[1]
3. ESC 2022 general recommendations in LQTS: avoid QT-prolonging drugs (crediblemeds.org), avoid and correct electrolyte abnormalities, and avoid genotype-specific triggers for arrhythmias (Class I, Level C) (1 mark).^[1] ESC 2022: beta-blockers, ideally non-selective (nadolol or propranolol), are recommended in LQTS with documented QT interval prolongation to reduce the risk of arrhythmic events (Class I, Level B); AHA/ACC/HRS 2017: in LQTS with a resting QTc greater than 470 ms, a beta blocker is recommended (COR I, LOE B-NR) (1 mark).^[1][2]
4. AHA/ACC/HRS 2017 high-risk features: QTc above 500 ms; LQT2 and LQT3 genotypes; females with LQT2; age below 40 years; onset of symptoms before 10 years of age; and prior cardiac arrest or recurrent syncope (half a mark each for any four).^[2]
5. ESC 2022: ICD implantation is recommended in LQTS patients who are symptomatic (arrhythmic syncope or haemodynamically non-tolerated VA) while receiving beta-blockers and genotype-specific therapies (Class I, Level C) (1 mark).^[1] ESC 2022: LCSD is indicated in symptomatic LQTS when ICD therapy is contraindicated or declined, or when a patient on beta-blockers and genotype-specific drugs with an ICD has multiple shocks or syncope due to VA (Class I, Level C); because half of patients have breakthrough events, LCSD is not an alternative to an ICD for high-risk patients (1 mark).^[1]

SAQ 2 (10 marks)

Practice scenario. Last week a 41-year-old man lost consciousness suddenly, without any prodrome, while resting in the evening. He has no other heart disease. A 12-lead ECG with high right precordial leads shows a spontaneous coved type 1 Brugada pattern, and phenocopies have been excluded.^[1][2]

1. Describe the type 1 Brugada ECG pattern and how detection can be improved. (2)^[1][2]
2. How does ESC 2022 treat a spontaneous versus an induced type 1 pattern in the diagnosis of Brugada syndrome? (2)^[1]
3. What general advice does ESC 2022 recommend for all patients with Brugada syndrome? (2)^[1]
4. His syncope is judged arrhythmic. Compare the ESC 2022 and AHA/ACC/HRS 2017 ICD rows that apply to him. (2)^[1][2]
5. He declines an ICD. Which drug options do the two guidelines give, and what limits the drug ESC 2022 names? (2)^[1][2]

Model answers — SAQ 2

1. AHA/ACC/HRS 2017: coved ST elevation in leads V1 or V2 positioned in the second, third or fourth intercostal space, either spontaneously or induced by a sodium channel-blocking drug, in the absence of other causes of ST elevation, with negative T waves in the right precordial leads (1 mark).^[2] AHA/ACC/HRS 2017: high electrode positioning in the second and third interspaces improves detection of a type 1 Brugada ECG (1 mark).^[2]
2. A spontaneous type 1 Brugada ECG pattern in a patient with no other heart disease diagnoses BrS (Class I, Level C), regardless of symptoms (1 mark).^[1] With an induced type 1 pattern and no other heart disease, BrS should be considered when there is at least one of arrhythmic syncope or nocturnal agonal respiration, a family history of BrS, or a family history of SD below 45 years with a negative autopsy and circumstances suspicious for BrS (Class IIa, Level C); an induced pattern alone may be considered as a diagnosis (Class IIb, Level C) (1 mark).^[1]
3. ESC 2022 recommends in all patients with BrS: avoiding drugs that may induce ST-segment elevation in the right precordial leads (brugadadrugs.org); avoiding cocaine, cannabis and excessive alcohol intake; and treating fever with antipyretic drugs (Class I, Level C) (2 marks).^[1]
4. ESC 2022: ICD implantation should be considered in patients with a type 1 Brugada pattern and an arrhythmic syncope (Class IIa, Level C) (1 mark).^[1] AHA/ACC/HRS 2017: with a spontaneous type 1 pattern and cardiac arrest, sustained VA or a recent history of syncope presumed due to VA, an ICD is recommended if meaningful survival of greater than 1 year is expected (COR I, LOE B-NR) (1 mark).^[2]
5. ESC 2022: quinidine should be considered in BrS patients who qualify for an ICD but have a contraindication, decline, or have recurrent ICD shocks (Class IIa, Level C), which fits him (half a mark); AHA/ACC/HRS 2017 recommends quinidine or catheter ablation with a spontaneous type 1 pattern and symptomatic VA in a patient who is not a candidate for, or declines, an ICD (COR I, LOE B-NR), a row written for symptomatic VA, so it applies to him if VA is documented (half a mark).^[1][2] ESC 2022: adverse effects of quinidine can occur in up to 37% of patients and quinidine is inaccessible in many countries; cilostazol, a phosphodiesterase-3 inhibitor, can be an alternative to quinidine (1 mark).^[1]