Clinical introduction

A 42-year-old women with a history of mitral regurgitation was playing tennis when she suddenly collapsed. Bystanders performed cardiopulmonary resuscitation. An automated external defibrillator revealed polymorphic ventricular tachycardia. The patient was shocked once with 200 J with return of spontaneous circulation. She was brought to the emergency department where her vitals revealed a heart rate of 133 beats/min, a respiratory rate of 30 breaths/min, an oxygen saturation of 89% and a blood pressure of 124/98 mm Hg. She was intubated. The chest X-ray revealed cardiomegaly. An ECG revealed sinus tachycardia, left axis deviation, Q waves in V1–V3, lateral T-wave inversions, a non-specific …