Clinical Introduction

A 63-year-old woman with a history of dwarfism presented with recurrent palpitations. She denied chest pain, dyspnoea or syncope. Her cardiac exam was notable for tachycardia at 188 bpm, hypotension (77/38) and no overt signs of heart failure. Cardiac markers were negative and her brain natriuretic peptide level was elevated at 687 pg/mL. An EKG revealed a left atrial tachycardia. She converted back to sinus rhythm after intravenous amiodarone. A chest X-ray demonstrated an enlarged cardiomediastinal silhouette. An initial transthoracic echocardiogram showed asymmetric septal hypertrophy, …