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Alcohol septal ablation versus surgical myectomy for HCM—the controversy continues

The presence of left ventricular outflow tract (LVOT) obstruction in patients with hypertrophic cardiomyopathy (HCM) is correlated with symptomatic status and cardiovascular mortality [1]. Surgical septal myectomy (SM) enables eradication of the dynamic LVOT gradient and symptomatic improvement while also affording the opportunity to correct any contribution of the mitral valve apparatus to LVOT obstruction. There exists ongoing controversy on whether SM or the less invasive alcohol septal ablation (ASA) is the most appropriate strategy in highly symptomatic, medication-refractory HCM patients with obstruction. Published comparisons consist mainly of single-center, non-randomized comparisons of the two strategies and meta-analyses of these case series [2]. Based on these observational datasets as well as expert opinion, current guidelines have preferentially recommended SM while reserving ASA for those in whom surgical risk is prohibitive [3]. However, the available evidence comparing both treatments remains equivocal with respect to improvements in clinical symptoms, hemodynamics, and mortality. As such, the growing widespread use of ASA amongst HCM patients reflects the deliberate decision-making of both patient and practitioner informed by relative procedural non-invasiveness and shorter recovery times, outweighing the documented increased risk of pacemaker dependence and potential re-intervention for treatment failure with ASA as compared to SM. As a randomized comparison of SM with ASA is unlikely to ever be performed [4], the choice between these two invasive therapies will ultimately be derived from the published reporting of institutional experience, “metaanalyses” and registries. In the current issue of Catheterization and Cardiovascular Interventions, Samardhi et al. [5] report their over 30 years experience invasively treating HCM patients. They describe 70 HCM patients who were either managed by SM (n1⁄4 23) or ASA (n1⁄4 47). Patient profiles differed between treatment strategies and were similar to previously published reports in that ASA patients were typically older, and more symptomatic. Both patient groups had similar echocardiographically determined LVOT gradients, septal thickness, significant mitral regurgitation, and systolic anterior motion of the mitral valve. Septal reduction by ASA and SM achieved significant improvements in symptoms and resting LVOT gradients with the non-novel finding of a trend toward lower gradients in the patients treated surgically. ASA patients more frequently required repeat procedures. Despite this, there was a trend toward a higher short-term and late (> 1 year) mortality in SM patients. Unlike previously published reports, the rate of permanent pacemaker insertion did not differ amongst the two groups. There certainly is value to reporting a collection of patient outcomes encompassing an observation period in excess of 30 years, however, the absence of insights into those factors influencing treatment assignment, including, but not limited to evolution of technique, changes in pharmacotherapy, and mortality-risk stratification in an era-dependent manner following the introduction of ASA is conspicuous. While overall outcomes are reportedly similar, median follow-up for symptomatic outcomes was less than 4 years and mortality less than 10 years amongst a population of SM and ASA patients whose mean age was less than 50 and 60 years, respectively. The current report does raise some questions and comments that should be posed. The reported population is atypical in that more than half of the ASA group had syncope as their presenting symptom. This is highly atypical in patients referred for invasive management of HCM. It would