Alcohol septal ablation for hypertrophic obstructive cardiomyopathy: focus on safety.

In this issue of the Swiss Medical Weekly, Streit et al. publish an observational study dealing with safety of alcohol septal ablation (ASA) for hypertrophic obstructive cardiomyopathy (HOCM) [1].The take-home message of their report is clear.ASA is not only effective but also a safe procedure. The most dreaded complications and consequences of ASA (sudden death, complete AV block and malignant tachyarrhytmias) are not often encountered. Since safety of non-pharmacological therapy of HOCM is in the thick of things now, I would like to comment on several issues raised in their paper and – moreover – to explain some standpoints of both opponents and proponents of this therapeutic approach. Hypertrophic cardiomyopathy (HCM) is a hereditary cardiac disease with unique pathophysiological characteristics and a great diversity of morphological, functional, and clinical features. HCM is commonly associated with systolic anterior motion of the anterior mitral valve leaflet and increased thickness of the interventricular septum that constitute the main conditions for the left ventricular outflow obstruction (obstructive HCM – HOCM). Typical symptoms are dyspnoea, angina pectoris, palpitations and syncope. Generally, the clinical course of HCM varies markedly and some patients remain asymptomatic throughout life, some have severe symptoms of heart failure or angina pectoris, and others die suddenly often in the absence of previous symptoms. Reported annual mortality is approximately 1% [2]. As shown previously in several studies, the presence of a resting outflow gradient is responsible for many symptoms and probably carries some prognostic significance. Therefore, surgical treatment primarily focused on myectomy of the part of redundant septal myocardium. Until the mid-nineties, surgical myectomy (or extended myectomy with mitral valve repair and partial excision of the papillary muscles) represented the gold standard in the treatment of highly symptomatic patients with HOCM. Surgery markedly reduces the outflow gradient and provides large improvements in objective measures of symptoms and functional status [2–4]. Unfortunately, mortality rates of less than 1 or 2% have only been achieved in exceptional surgical centres with an extensive experience and numerous performed procedures. Moreover, it seems to be probable that many worse surgical results are underreported. The idea of inducing a septal infarction by endovascular techniques was suggested by the observation of Ulrich Sigwart that myocardial function and outflow gradient could be suppressed by occlusion of the supplying artery during balloon angioplasty. Additionally, the new concept of septal ablation was supported by the old radiological technique with use of alcohol injection to produce necrosis of the targeted tissue. As the first, Ulrich Sigwart published his experience with “non-surgical myocardial reduction” of three patients with HOCM in 199 . He injected several millilitres of pure alcohol into septal branch of the left anterior descending coronary artery to specifically induce limited necrosis of hypertrophied interventricular septum with its subsequent shrinkage and outflow gradient elimination [ ]. Since that time several modifications of the original technique have been described and thousands of patients have been treated. Thus, the endovascular septal procedures are several times more frequent than surgical procedures. It is likely that the main reasons for that are as follows: (1) the relatively simple catheteriThe Rules of Cider House