Arrhythmias and Conduction Disorders (ECG, Tachycardia, Heart Block) MCQs

Medicine · 85 free questions with answers & explanations.

  1. A 28-year-old woman with no structural heart disease presents with recurrent episodes of sudden-onset regular palpitations at 180 bpm, with abrupt termination. ECG during palpitations shows narrow complex tachycardia at 180/min with no visible P waves. The tachycardia terminates with vagal maneuvers. What is the most likely mechanism?
  2. A 72-year-old man is found to have an ECG showing a PR interval of 0.28 sec with consistent 1:1 AV conduction. No dropped beats occur. He is asymptomatic. What is the diagnosis and appropriate management?
  3. A 55-year-old woman is brought to the ER with palpitations, dizziness, and near-syncope. 12-lead ECG shows a wide complex tachycardia at 195 bpm with AV dissociation and positive QRS concordance across V1–V6 with no RS complex visible. What is the most likely diagnosis?
  4. A 72-year-old man is found to have a permanent pacemaker (DDD) implanted 3 years ago for complete heart block. He now presents with syncope. ECG shows a rate of 38 bpm with ventricular pacing spikes not followed by QRS complexes. The non-paced native rate is absent. What is the most likely pacemaker malfunction?
  5. A 50-year-old man with no structural heart disease has symptomatic paroxysmal AF. Rate control has not been satisfactory. He is now being considered for rhythm control. The EAST-AFNET 4 trial demonstrated which key finding relevant to AF rhythm control strategy?
  6. A 62-year-old woman presents with palpitations. ECG shows a regular tachycardia at 165 bpm with narrow QRS complexes and a pseudo-R' wave visible in lead V1 (retrograde P wave). Vagal manoeuvres terminate the tachycardia transiently. What is the most likely mechanism?
  7. In Brugada syndrome, spontaneous type 1 pattern (coved ST elevation ≥2mm in V1–V2 with RBBB morphology) is sufficient for diagnosis. The predominant ion channel implicated is loss-of-function mutation in SCN5A. How does fever precipitate arrhythmia in Brugada syndrome?
  8. The AVNRT (atrioventricular nodal re-entrant tachycardia) mechanism involves a dual-pathway AV node. In typical (slow-fast) AVNRT, the P wave relationship to QRS is:
  9. Long QT syndrome Type 2 (LQT2) is caused by loss-of-function mutations in KCNH2 (hERG), reducing IKr. Which specific trigger most commonly provokes arrhythmia in LQT2 compared with LQT1?
  10. A 45-year-old man presents with palpitations. ECG shows a regular narrow-complex tachycardia at 170 bpm with P waves visible immediately after the QRS (retrograde, with RP interval < PR interval). Carotid sinus massage terminates the arrhythmia. The mechanism is:
  11. A 68-year-old woman with hypertension and paroxysmal AF has a CHA₂DS₂-VASc score of 4. She has a HAS-BLED score of 2. According to ESC 2020 AF guidelines, the MOST appropriate antithrombotic strategy is:
  12. A 55-year-old man is admitted with complete heart block (third-degree AV block) following inferior STEMI. His rate is 42 bpm with a stable blood pressure of 90/60 mmHg. The CORRECT initial management is:
  13. A 52-year-old woman with paroxysmal atrial fibrillation undergoes pulmonary vein isolation (PVI) via radiofrequency catheter ablation. The mechanism by which pulmonary vein isolation prevents AF recurrence is:
  14. A 48-year-old man presents with syncope. ECG shows PR interval 280 ms, QRS duration 140 ms with LBBB morphology, and QT 480 ms. His echo shows LV wall motion abnormality. He undergoes EP study showing HV interval of 90 ms (normal <55 ms) and inducible ventricular tachycardia. The most appropriate intervention is:
  15. A 60-year-old man with paroxysmal AF on anticoagulation undergoes catheter ablation (pulmonary vein isolation). Three months post-procedure, he develops recurrent AF. His CHA₂DS₂-VASc score is 3. He has no contraindication to anticoagulation. What is the recommended anticoagulation strategy after recurrence?
  16. A 55-year-old woman has a 12-lead ECG showing: regular wide-complex tachycardia at 175/min, AV dissociation, capture beats, and fusion beats. Blood pressure is 90/60 mmHg. What is the most accurate diagnosis and appropriate immediate management?
  17. A 58-year-old woman with paroxysmal AF and CHA₂DS₂-VASc score of 4 is anticoagulated on apixaban. She undergoes electrical cardioversion. How long should anticoagulation be continued after successful cardioversion?
  18. A 45-year-old man with WPW syndrome and AF develops a rapid, irregular wide-complex tachycardia (rate 260 bpm) with a delta wave visible during slower beats. He is haemodynamically stable. Which pharmacological intervention is contraindicated and why?
  19. A 62-year-old woman with persistent atrial fibrillation (AF) and CHA2DS2-VASc score of 4 has been on warfarin for 3 years. Her time in therapeutic range (TTR) is consistently 58%. She is keen to avoid INR monitoring. According to 2023 ESC AF guidelines, the preferred next step in anticoagulation management is:
  20. A 28-year-old man presents with palpitations. ECG shows a short PR interval (0.1 s), delta waves, and wide QRS. He develops a regular narrow-complex tachycardia at 180 bpm. The mechanism of this tachycardia in Wolff-Parkinson-White (WPW) syndrome is:
  21. A 55-year-old man has a narrow complex regular tachycardia at 170 bpm. Adenosine 6 mg IV is given and causes brief AV block, revealing no change in the tachycardia rate — the rhythm continues unchanged through the AV nodal block. The most likely diagnosis is:
  22. A 68-year-old man with non-valvular AF has a CHA₂DS₂-VASc score as follows: age 68 (1 point), hypertension (1 point), heart failure (1 point), diabetes (1 point). Total score = 4. His HAS-BLED score is 2. What is the annual stroke risk and should anticoagulation be initiated?
  23. A 55-year-old woman with paroxysmal atrial fibrillation (CHA2DS2-VASc score 3: female sex, hypertension, age 65) is being considered for catheter ablation. After successful ablation, when can anticoagulation be stopped according to current ESC 2020 AF guidelines?
  24. A 45-year-old man with WPW syndrome on ECG (delta waves, short PR) is found to have pre-excited AF during Holter monitoring with the shortest pre-excited RR interval of 200 ms. He has no symptoms of syncope or palpitations. What does this finding imply and what management is recommended?
  25. A 68-year-old man with persistent atrial fibrillation and CHA2DS2-VASc score of 4 (hypertension, age ≥65, diabetes, female sex absent). He has eGFR 52 mL/min. The PREFERRED anticoagulation is:
  26. A 45-year-old man has recurrent palpitations and ECG shows a short PR interval (0.10 s), delta wave, and a wide QRS complex during sinus rhythm. During an episode, he develops a rapid irregular tachycardia at 240 bpm. The CONTRAINDICATED drug in this scenario is:
  27. A 62-year-old woman with persistent atrial fibrillation (AF) has a CHA₂DS₂-VASc score of 4 (hypertension, age 62, diabetes, female sex). She has no contraindications to anticoagulation. Per 2023 ESC/ACC guidelines, which anticoagulation strategy is preferred?
  28. A patient presents with wide-complex tachycardia at rate 180/min. ECG shows atrioventricular dissociation, capture beats, and fusion beats. What is the most likely diagnosis and immediate management?
  29. A 65-year-old man with persistent atrial fibrillation (>12 months), LVEF 55%, CHA₂DS₂-VASc score of 3 is on warfarin (INR 2.5). He now requires anticoagulation optimisation. A direct oral anticoagulant (DOAC) is preferred over warfarin in AF because of:
  30. A 35-year-old woman presents with sudden palpitations and light-headedness. ECG during the episode shows a regular narrow-complex tachycardia at 185 bpm with no clearly visible P waves between QRS complexes; a pseudo-R' in lead V1 is noted. Vagal maneuvers terminate the tachycardia. The MOST likely diagnosis is:
  31. A 50-year-old man presents with syncope. ECG shows PR interval gradually prolonging over several beats followed by a dropped QRS (Wenckebach phenomenon), and this cycle repeats. The level of block is most likely:
  32. A 55-year-old man has palpitations. ECG shows: regular narrow-complex tachycardia at 175/min, P waves not visible before QRS, short RP interval with P waves visible in the ST segment (RP < PR). Which is the most likely arrhythmia?
  33. A 68-year-old woman with hypertensive heart disease develops atrial fibrillation with rapid ventricular response (130 bpm). Her BP is 90/60 mmHg and she is diaphoretic. What is the immediate management?
  34. A 55-year-old man with paroxysmal atrial fibrillation has CHA₂DS₂-VASc score of 3 (hypertension, age 65–74, diabetes). He has HAS-BLED score of 2. Renal function is normal. Which anticoagulation is preferred per current guidelines?
  35. A 35-year-old woman presents to the ER with SVT at 180 bpm. BP is 110/70 mmHg. She has no structural heart disease. Vagal manoeuvres fail. What is the drug of first choice for acute termination?
  36. A 58-year-old man with persistent atrial fibrillation has a CHA₂DS₂-VASc score of 3. He has no contraindications to anticoagulation. What is the recommended stroke prevention strategy per 2023 ACC/AHA/ACCP Atrial Fibrillation guidelines?
  37. A 32-year-old woman with structurally normal heart has recurrent palpitations with sudden onset and offset. ECG during palpitation shows regular narrow-complex tachycardia at 180 bpm with RP interval shorter than PR interval and pseudo-S waves in inferior leads. She has no delta waves on resting ECG. What is the most likely mechanism?
  38. A 28-year-old woman presents with recurrent paroxysmal SVT. ECG during tachycardia shows a narrow complex tachycardia at 185 bpm with no visible P waves (P waves buried in QRS). Baseline ECG is normal. Carotid sinus massage terminates the episode. The most likely mechanism and first-line long-term prophylactic treatment are:
  39. A 60-year-old man with atrial fibrillation has a CHA2DS2-VASc score of 4 (prior stroke, hypertension, age 60–74, diabetes). He has no contraindications. Current guidelines recommend:
  40. A 58-year-old man with paroxysmal atrial fibrillation has a CHA₂DS₂-VASc score of 3 (hypertension, age 58–74, male sex). He has a HAS-BLED score of 2. Which statement regarding anticoagulation is CORRECT per current ACC/AHA guidelines?
  41. A 52-year-old woman without structural heart disease presents with episodic palpitations. A 12-lead ECG during an episode shows a narrow QRS tachycardia at 185 bpm, with a short RP interval (RP < PR) and a pseudo-r' notch in lead V1. What is the MOST likely diagnosis?
  42. A 72-year-old man with persistent atrial fibrillation (AF) has a CHA₂DS₂-VASc score of 4 (age 72, hypertension, diabetes, prior TIA). He is started on a NOAC. Which NOAC is preferred in patients with non-valvular AF and CKD stage 3b (eGFR 38 mL/min)?
  43. A 22-year-old woman presents with recurrent episodes of rapid regular palpitations (rate 180 bpm) with abrupt onset and offset, no structural heart disease. ECG during tachycardia shows narrow complex, retrograde P waves after QRS (short RP tachycardia, RP interval 80 ms). What is the most likely mechanism?
  44. A 55-year-old man with persistent atrial fibrillation and a CHA₂DS₂-VASc score of 4 is started on anticoagulation. He is also started on amiodarone for rate/rhythm control. After 6 months, his TSH is suppressed to <0.01 mIU/L with elevated free T4 and T3. CT scan shows a vascular pattern on thyroid Doppler (type 2 amiodarone-induced thyrotoxicosis — AIT). The treatment of choice for type 2 AIT is:
  45. A 24-year-old athlete collapses during a marathon. ECG on recovery shows delta waves, short PR interval, and a wide QRS complex. He is asymptomatic between episodes. Electrophysiology study reveals an accessory pathway with anterograde effective refractory period (AERP) of 220 ms. This finding indicates:
  46. A 55-year-old woman with persistent atrial fibrillation (CHA₂DS₂-VASc score = 4) is on apixaban. She undergoes cardioversion. Current ESC 2024 AF guidelines recommend anticoagulation be continued for how long after successful cardioversion to a sinus rhythm?
  47. A 48-year-old man presents with palpitations and narrow complex tachycardia at 180 bpm. Vagal manoeuvres terminate the arrhythmia. An ECG post-termination shows a short PR interval of 100 ms and a delta wave. Which syndrome is this and what is the arrhythmia mechanism?
  48. A 70-year-old man with syncope has an ECG showing alternating LBBB and RBBB morphology. Which type of heart block/conduction disease does this represent, and what is the treatment?
  49. A 70-year-old man with permanent atrial fibrillation, hypertension, diabetes, and eGFR 40 mL/min is being anticoagulated. CHA₂DS₂-VASc score is 5. Which oral anticoagulant is most appropriate?
  50. A 40-year-old man with structurally normal heart has recurrent narrow-complex regular tachycardia (SVT) with heart rate 190/min. ECG during sinus rhythm shows a delta wave and short PR interval. He had 3 episodes requiring adenosine termination in the past year. What is the most appropriate management?
  51. A 55-year-old man with persistent atrial fibrillation (duration >12 months) and a CHA₂DS₂-VASc score of 4 has a HAS-BLED score of 2. Which anticoagulation strategy is appropriate?
  52. A 28-year-old woman presents with recurrent episodes of palpitations with sudden onset and offset, heart rate 180 bpm, regular narrow complex tachycardia, and a short PR interval with delta waves on sinus rhythm ECG. Electrophysiology study confirms a left lateral accessory pathway. What is the definitive treatment?
  53. A 65-year-old man has a 12-lead ECG showing fixed heart rate of 72 bpm with paced spikes preceding each QRS complex. On Holter monitoring, native P waves are present but not sensed by the device, and there are competitive paced beats. Which pacemaker malfunction is described?
  54. A 55-year-old woman with non-valvular atrial fibrillation (CHA₂DS₂-VASc score 4) refuses anticoagulation due to fear of bleeding. She asks about left atrial appendage occlusion (LAAO). Per ACC/AHA guidelines, LAAO with the Watchman device is indicated in:
  55. A 22-year-old athlete collapses during a football match. ECG shows a short PR interval (0.10 s), a delta wave, and a widened QRS. He has no family history. Which tachyarrhythmia is he at risk of, and why is digoxin contraindicated?
  56. A 75-year-old man with complete heart block (CHB) develops syncope. His resting ECG shows P waves at 72 bpm with complete AV dissociation and an escape rhythm at 34 bpm (wide QRS). What is the IMMEDIATE definitive treatment?
  57. A 58-year-old man is found to have atrial fibrillation. He has hypertension, diabetes, and a prior TIA. What is his CHA₂DS₂-VASc score and the recommended management?
  58. A 45-year-old woman develops regular narrow-complex tachycardia at 170 bpm with a retrograde P wave visible shortly after the QRS in lead V1 (short RP tachycardia with RP < PR). Vagal manoeuvres fail. What is the treatment of choice?
  59. A 68-year-old man with ischaemic cardiomyopathy (LVEF 28%) experiences recurrent sustained ventricular tachycardia despite optimal medical therapy including amiodarone. An ICD was placed 6 months ago with multiple appropriate shocks. What additional intervention has been shown to reduce ICD shocks?
  60. A 55-year-old woman has recurrent paroxysmal supraventricular tachycardia (PSVT). ECG during an episode shows narrow QRS tachycardia at 180 bpm with retrograde P waves within the QRS. What is the mechanism and long-term ablation target?
  61. A patient with symptomatic sick sinus syndrome (bradycardia-tachycardia syndrome) requires pacing. Which pacing mode is preferred to reduce the risk of pacemaker syndrome and atrial fibrillation?
  62. A 62-year-old man with persistent AF and a CHA₂DS₂-VASc score of 3 (prior stroke, hypertension) has had good rate control but remains in AF at 6 months. He is on rivaroxaban. The EAST-AFNET 4 trial (2020) showed that early rhythm control in recently diagnosed AF (within 1 year):
  63. A 28-year-old man has recurrent palpitations with sudden onset and termination. ECG during tachycardia shows a narrow-complex regular tachycardia at 185 bpm with retrograde P waves in the ST segment (RP interval <70 ms). Which is the MOST likely mechanism?
  64. A 22-year-old athlete collapses after vigorous exercise. He is resuscitated from ventricular fibrillation. ECG in normal sinus rhythm shows ST elevation in V1-V2 with right bundle branch block morphology, and the same pattern was previously documented. Genetic testing confirms a SCN5A mutation. The ONLY evidence-based secondary prevention is:
  65. A 24-year-old woman with recurrent paroxysmal SVT is found to have a delta wave, short PR interval, and wide QRS on resting ECG. She has a history of syncope during episodes. EP study reveals a left lateral accessory pathway with shortest pre-excited RR interval of 210 ms during atrial fibrillation. The MOST appropriate management is:
  66. A 70-year-old man is on digoxin for AF rate control. He presents with bradycardia (HR 38 bpm), nausea, and confusion. ECG shows regularised slow ventricular rate with junctional rhythm. Serum digoxin is 3.8 ng/mL. Potassium is 5.8 mmol/L. The mechanism of digoxin toxicity causing this ECG pattern is:
  67. A 55-year-old man develops palpitations and pre-syncope. 12-lead ECG shows delta waves, short PR interval (0.10 s), wide QRS, and a rapid irregular wide-complex tachycardia at 200 bpm during a spontaneous episode. He is hemodynamically stable. What is the drug of choice for acute pharmacological management?
  68. A 45-year-old woman is being evaluated for recurrent syncope. Tilt-table testing is positive (hypotension + bradycardia at 60° head-up tilt after 15 minutes, type 2B — VASIS classification). ECG and echo are normal. What is the most appropriate management?
  69. A 55-year-old woman presents with palpitations. 12-lead ECG shows a regular wide-complex tachycardia at 160 bpm. The Brugada criteria for distinguishing VT from SVT with aberrancy include which finding as MOST specific for VT?
  70. A 62-year-old man with paroxysmal AF and CHA2DS2-VASc score of 4 refuses anticoagulation due to recurrent falls. Which assessment tool should be used to evaluate bleeding risk before making the final decision on anticoagulation?
  71. A 45-year-old man with WPW syndrome develops atrial fibrillation with rapid ventricular response (260 bpm) showing irregular wide QRS complexes. Which drug is ABSOLUTELY CONTRAINDICATED?
  72. Brugada syndrome is characterised by ST elevation in leads V1–V3. The spontaneous (Type 1) Brugada ECG pattern shows which SPECIFIC morphology?
  73. In long QT syndrome (LQTS), the sodium channel mutation (LQT3 due to SCN5A) has a specific clinical characteristic regarding arrhythmia timing that distinguishes it from LQT1 and LQT2:
  74. A 32-year-old woman presents with palpitations. Her ECG shows a regular narrow complex tachycardia at 175 bpm with retrograde P waves visible in the ST segment. Adenosine terminates the episode. Electrophysiology study is planned. What is the most likely mechanism?
  75. A patient with Brugada syndrome has recurrent ventricular fibrillation episodes. Current guidelines indicate he should receive an ICD. Which drug, used in the setting of recurrent ICD shocks in Brugada syndrome, acts by blocking transient outward current (Ito) and has demonstrated efficacy in suppressing electrical storms?
  76. A 52-year-old man with paroxysmal atrial fibrillation (no structural heart disease) has had 3 symptomatic episodes over 6 months. His CHA₂DS₂-VASc score is 2 (hypertension, age). He requests rate vs. rhythm control. The EAST-AFNET 4 trial (2020) significantly changed the AF management paradigm by demonstrating:
  77. A 48-year-old woman with Wolff-Parkinson-White syndrome develops AF with rapid ventricular response (HR 220 bpm, irregular, wide and pre-excited complexes). BP is 90/60 mmHg. Which immediate pharmacological choice is most dangerous in this setting?
  78. A 50-year-old woman with paroxysmal atrial fibrillation (CHA₂DS₂-VASc score 3) is in sinus rhythm on rate control. She prefers rhythm control. Flecainide is chosen. Which condition would CONTRAINDICATE flecainide use?
  79. A 72-year-old man presents with syncope. ECG shows alternating right and left bundle branch block pattern. What does this represent and what is the management?
  80. A 52-year-old woman with paroxysmal atrial fibrillation (CHA2DS2-VASc score 3) is being started on flecainide as 'pill-in-the-pocket' therapy. She has no structural heart disease and normal LV function. Which condition MUST be ruled out before initiating flecainide therapy?
  81. A 78-year-old man with complete heart block (CHB) who had a permanent pacemaker implanted 3 years ago presents with pre-syncope. Pacemaker check shows it is programmed VVI at 60 ppm. His intrinsic rate is 38 bpm. ECG shows pacing spikes not consistently followed by QRS complexes. What is the most likely cause?
  82. A 70-year-old man with persistent atrial fibrillation (duration >48 hours) has a CHA2DS2-VASc score of 4. He is haemodynamically stable. Rate control is achieved with bisoprolol. Regarding anticoagulation: when can cardioversion be performed after initiating rivaroxaban?
  83. A 55-year-old man presents with a regular wide-complex tachycardia at 180 bpm. He has a history of previous MI. ECG shows AV dissociation with fusion beats. Which is the MOST likely diagnosis?
  84. A 70-year-old man with atrial fibrillation and a CHA2DS2-VASc score of 4 is prescribed anticoagulation. He develops a fall-related intracranial haemorrhage on warfarin with INR 2.6. After recovery, which anticoagulation option is MOST appropriate on reassessment?
  85. A 45-year-old woman presents with palpitations and syncope. ECG shows a short PR interval (0.1 sec), delta waves in V1-V4, and wide QRS. She has documented supraventricular tachycardia. Which treatment carries the highest risk of precipitating ventricular fibrillation in this patient?
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