Broad complex tachycardia in a 46-year-old man.

A 46-year-old South Asian male with no comorbidity presented with palpitations and presyncope. There was no history of chest pain, and no family history of premature atherosclerosis, cardiomyopathy or sudden death. The presenting ECG is shown in figure 1A. Routine blood tests, including full blood count and inflammatory markers, were unremarkable. Admission troponin I was elevated at 470 ng/L (normal 0–34 ng/L), peaking at 1450 ng/L. Serum angiotensin-converting enzyme was marginally elevated at 63 U/L (normal 8–52 U/L). Echocardiography demonstrated normal biventricular dimensions, with moderate biventricular systolic impairment. Invasive angiography revealed unobstructed coronary arteries. Cardiac magnetic resonance (CMR) imaging demonstrated marked hypokinesia of the interventricular septum and right ventricular outflow tract free …