A 13 year old boy was investigated for recurrent exertional syncope. Chest x ray showed a globular cardiac silhouette and 12 lead ECG suggested left ventricular hypertrophy with strain pattern. Transthoracic echocardiography (TTE) revealed basal septal hypertrophy with systolic anterior motion (SAM) of the mitral valve. A diagnosis of hypertrophic cardiomyopathy (HCM) was made and β blockers were started. Twenty years later, the patient reported symptoms of gradually worsening dyspnoea. The ECG was unchanged and TTE revealed mild apical but no basal hypertrophy. Additionally, there was a reduced A wave on mitral pulsed wave Doppler and impaired left ventricular long axis function suggestive of a restrictive filling pattern. Repeat TTE three years later confirmed mild apical hypertrophy in the absence of basal hypertrophy or SAM. The patient underwent cardiovascular magnetic resonance (CMR). This demonstrated dilatation of all four cardiac chambers with globally impaired biventricular function and functional mitral regurgitation. The left ventricular apex was thinned with prominent trabeculations (upper panels A–D). There was late gadolinium enhancement of the epicardium and mid wall in the basal and mid septal and anterior walls in association with varying degrees of wall motion abnormality (lower panels A–D). These features suggested a diagnosis of dilated cardiomyopathy secondary to isolated left ventricular non-compaction (IVNC). IVNC is an increasingly recognised and important cause of heart failure and ventricular arrhythmias. This case with late presentation illustrates the complementary role of CMR with late gadolinium enhancement in the evaluation of cases of suspected apical HCM.

Panels A, B: four chamber view in (A) diastole and (B) systole. Panels C, D: ventricular long axis view in (C) diastole and (D) systole. There is heavy trabeculation of the apex of the left ventricle characteristic of IVNC (white arrows) with moderate mitral regurgitation (black arrow).

Panels A, B: four chamber (A) and basal short axis (B) views. Epicardial late gadolinium enhancement is present in the basal and mid septal wall (white arrows). Panels C, D: vertical long axis (C) and mid short axis (D) views. Mid wall late gadolinium enhancement is present in the anterior wall (white arrows).