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Section of Cardiovascular Surgery, Mayo Clinic, 200 First St, SW, Rochester, MN 55905
(Email: jdearani{at}mayo.edu).
It has been 50 years since the initial report of the disease that is now recognized as hypertrophic cardiomyopathy (HCM). During the past 5 decades there have been pendular shifts in the enthusiasm for surgical relief of dynamic outflow obstruction. Improvements in the understanding of the hemodynamics, pathophysiology, and surgical techniques has led to a re-emergence of surgical septal myectomy (SSM) as an appropriate therapy for patients with severe symptoms that were refractory to pharmacologic therapies, which is an indication that has not changed to this day. The SSM has also been challenged by the development and investigation of novel, seemingly "less invasive," yet still interventional therapies: dual-chamber pacing and percutaneous alcohol septal ablation. Despite these challenges, SSM has continued to rise from the fray as the most definitive therapy for relief of symptoms.
In this issue, Smedira and colleagues [1] report their surgical results of over 300 patients with obstructive HCM who had a myectomy as the "major" procedure. Strengths of this review include confirmation of durable hemodynamic results, low procedure-related mortality, nonfatal complications, and excellent long-term survival. Limitations of this investigation include nonuniform hemodynamic (echocardiographic) follow-up and the exclusion of nearly 400 other myectomy patients during the same time period. Nevertheless, it is important to consider how these data fit with other publications and what this means to the cardiologist, surgeon, and patient.
Many reports have documented dramatic and definitive hemodynamic benefits of SSM. Indeed, the results of the current study parallel our own experience; low operative mortality (< 1%), markedly improved quality of life, and excellent late survival. Importantly, recent studies have demonstrated a survival advantage in patients with obstructive HCM who undergo SSM compared with patients who have obstructive HCM managed without surgery (late survival equivalent to that of an age-matched general population, ie,
1% annual cardiac mortality rate). In addition, there are new data that suggest the rate of sudden cardiac death or appropriate implantable cardioverter defibrillator (ICD) discharge are reduced, but importantly are not eliminated after SSM. Thus, SSM can be expected to safely improve symptoms and long-term survival.
How does this compare with the current alternative technique: percutaneous alcohol septal ablation? Alcohol ablation creates a strategically placed iatrogenic myocardial infarction (ie, a scar). Currently published data suggest that procedural success is in the range of 75% to 80%, and among those successes, symptomatic improvement in the short-term and intermediate term is comparable with a myectomy. However, despite the "less invasive" nature of this technique, the procedure-related morbidity and mortality are not lower than SSM, and in some series they are higher. Importantly, there are no data indicating improved late survival after alcohol septal infarction. From a clinical investigation standpoint, it will be difficult for any procedure to show incremental benefit on the robust morbidity, mortality, hemodynamic, symptomatic, and survival benefits provided by SSM.
Finally, among centers with substantial focus on HCM in which both the SSM and septal ablation are performed, the SSM myectomy is the preferred and proven therapy, whereas septal ablation is considered an alternative approach if surgical risk or other circumstances render surgery less attractive. A separate, but important consideration is risk of sudden death related to arrhythmia; although postoperative rates of sudden death are very low, risk is not zero, and patients should be evaluated longitudinally regarding the need for medical treatment or ICD therapy, or both.
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