Arrhythmias USMLE Step 1 Practice Question
A 68-year-old man with a history of hypertension and left ventricular hypertrophy presents to the emergency department after experiencing syncope during morning jogging. His wife reports he collapsed without warning and recovered consciousness within 30 seconds. Vital signs: BP 148/92 mmHg, HR 78 bpm (currently regular), RR 16, O2 sat 98% RA. Physical examination reveals a regular pulse at present and a grade II/VI systolic ejection murmur at the left sternal border. A 12-lead ECG is obtained (see below). The QTc interval measures 520 ms (normal <450 ms in males). Troponin I is negative. An echocardiogram shows mild concentric left ventricular hypertrophy with preserved ejection fraction. During continuous cardiac monitoring in the ICU, the patient experiences an episode of rapid polymorphic ventricular tachycardia with a characteristic appearance of the QRS complexes appearing to rotate around the isoelectric line before spontaneously terminating. Which of the following is the most likely diagnosis?
Answer choices
- ABrugada syndrome with fever-triggered ventricular fibrillation
- BLong QT syndrome with torsades de pointesCorrect answer
- CHypertrophic cardiomyopathy with exercise-induced ventricular tachycardia
- DEarly repolarization pattern with idiopathic ventricular fibrillation
- ECatecholaminergic polymorphic ventricular tachycardia triggered by exercise
- FDilated cardiomyopathy with secondary atrial fibrillation
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