Hypertrophic cardiomyopathy (HCM) is a genetic condition characterised by the presence of otherwise unexplained left ventricular hypertrophy. The clinical spectrum of the disease is remarkably heterogeneous, ranging from individuals with normal life expectancy and minimal symptoms to those with lives severely restricted by breathlessness and chest pain and potentially lethal arrhythmias. Around 25% of patients with HCM have dynamic left ventricular outflow tract (LVOT) obstruction caused by both protrusion of the hypertrophied interventricular septum into the outflow tract and systolic anterior motion of the mitral valve. The presence of outflow tract obstruction is a powerful predictor of adverse prognosis.¹ While it is not yet clear whether therapeutic relief of obstruction improves prognosis (see below), there is good evidence that surgical procedures to reduce obstruction are effective in relieving symptoms in patients that have not responded to medical treatment (for example, β blockers, disopyramide). Traditionally, septal myectomy (resection of that portion of the septum responsible for obstruction) has been the surgical technique of choice.² Over the last decade alcohol septal ablation (ASA) has been developed as an alternative to open heart surgery. This percutaneous technique produces a reduction in outflow tract obstruction localised infarction of the septal myocardium by alcohol injection into the appropriate septal artery.³ Correct localisation of the infarction is provided by myocardial contrast echocardiography.⁴

INDICATIONS FOR ALCOHOL SEPTAL ABLATION

Prognosis

There is no definitive randomised data to suggest that either ASA or septal myectomy have an effect on prognosis. Recently, a retrospective analysis of 1337 patients with HCM showed that those symptomatic patients with obstruction that underwent septal myectomy had a better long-term prognosis than those that were medically treated.⁵ While these findings are of interest they should not be extrapolated to a recommendation that septal myectomy should be recommended for asymptomatic patients with LVOT obstruction—firstly because such patients …