A 65 year old man was admitted with syncope. An ECG in the emergency department revealed ventricular tachycardia with haemodynamic compromise necessitating electrical cardioversion. Serum electrolytes and post-cardioversion ECG were normal. Two dimensional transthoracic echocardiography showed moderate concentric left ventricular hypertrophy with normal systolic function (panels A, B). Cardiac catheterisation showed no evidence of obstructive coronary artery disease. The left ventriculogram was peculiar with a double wall appearance to the left ventricular free wall (panel C). A cardiac biopsy …