METHODS

Seventeen patients (9 males and 8 females) with non-obstructive HCM were prospectively enrolled in the study. The diagnosis of HCM had been made between the ages of 1 month and 13 years (mean (SD) 71 (54) months). At the time of the study their ages ranged from 16 months to 16.5 years (mean 123 (70) months). HCM was defined by the presence of a hypertrophied, non-dilated left ventricle, in the absence of underlying cardiac, systemic disease or syndromic conditions. Four patients had a family history of HCM and two had a family history of premature (less than 50 years) sudden cardiac death of a first degree relative. At the time of the study, no patients were receiving treatment.

Seven patients complained of moderate exertional dyspnoea; no patient had a history of chest pain or syncope. Standard 12 lead ECG showed that seven patients had abnormal repolarisation. On 24 hour monitoring, all patients were in stable sinus rhythm, and no arrhythmia was recorded. Ten patients underwent exercise testing and none had hypotension, arrhythmias or ischaemia during exercise. Five patients …