IBHRE - International Board of Heart Rhythm Examiners Arrhythmia Interpretation and Diagnosis Questions and Answers

Question 1

A 65-year-old male with a history of myocardial infarction presents with a regular, wide complex tachycardia at 150 bpm. The ECG shows a QRS duration of 160 ms, a northwest axis, and evidence of AV dissociation. In lead V1, there is a monophasic R wave. Which of the following is the most likely diagnosis?

Accepted Answer

Ventricular tachycardia

Answer

Ventricular tachycardia (VT) is the most likely diagnosis. Several features in the description strongly suggest VT over a supraventricular rhythm with aberrancy. These include a history of structural heart disease (prior MI), QRS duration >140 ms, a northwest axis (extreme axis deviation), and the presence of AV dissociation. A monophasic R wave in V1 is also a classic morphological criterion for VT.

Question 2

A 58-year-old patient presents to the clinic for a follow-up visit. They mention having intermittent, crushing chest pain over the past week, but are currently pain-free. The ECG shows deeply inverted, symmetric T-waves in leads V2 and V3, with minimal (<1mm) ST-segment elevation and preserved R-wave progression. What is the most likely diagnosis?

Accepted Answer

Wellens' syndrome

Answer

The ECG findings described are characteristic of Wellens' syndrome (specifically Type B). This pattern, often seen when the patient is pain-free, is highly specific for a critical, proximal stenosis of the left anterior descending (LAD) artery and indicates a high risk of an impending large anterior wall myocardial infarction.

Question 3

Which of the following ECG findings is the defining characteristic of a Mobitz Type II second-degree atrioventricular block?

Accepted Answer

A constant PR interval in all conducted beats before an unexpected, non-conducted P-wave.

Answer

Mobitz Type II second-degree AV block is characterized by a constant and unchanging PR interval in the conducted beats preceding a suddenly dropped QRS complex (a non-conducted P-wave). Unlike Mobitz Type I (Wenckebach), there is no progressive lengthening of the PR interval. This type of block is typically located in the His-Purkinje system and carries a higher risk of progressing to complete heart block.

Question 4

A patient with a dual-chamber pacemaker presents with palpitations. Device interrogation reveals a tachycardia with a ventricular paced rate at the programmed upper tracking rate. The intracardiac electrogram shows a consistent 1:1 ventriculoatrial (VA) conduction pattern where a ventricular paced event is followed by a retrograde atrial sensed event, which then triggers the next ventricular paced event. What is the most likely diagnosis?

Accepted Answer

Pacemaker-mediated tachycardia (PMT)

Answer

This scenario describes a classic endless loop or pacemaker-mediated tachycardia (PMT). PMT is a reentrant arrhythmia where the pacemaker forms the antegrade limb (atrial sensing to ventricular pacing) and the patient's native conduction system provides the retrograde limb (ventricle to atrium). The cycle of V-pace -> retrograde P-wave -> A-sense -> V-pace maintains the tachycardia.

Question 5

Which of the following ECG findings is considered the only potentially diagnostic pattern for Brugada syndrome without provocative testing?

Accepted Answer

Coved-type ST-segment elevation of ≥2 mm in at least one right precordial lead (V1-V3) followed by a negative T-wave.

Answer

The Type 1 Brugada pattern is the only ECG finding considered diagnostic of Brugada Syndrome when associated with clinical criteria (e.g., syncope, family history of sudden death). It is defined by a coved-type ST-segment elevation of 2 mm or more in at least one of the right precordial leads (V1, V2, or V3), followed by a negative or biphasic T-wave.

IBHRE - International Board of Heart Rhythm Examiners Practice Test

IBHRE - International Board of Heart Rhythm Examiners Practice Test

IBHRE - International Board of Heart Rhythm Examiners Arrhythmia Interpretation and Diagnosis Questions and Answers