Response to Letter Regarding Article, “Outcome of Alcohol Septal Ablation for Obstructive Hypertrophic Cardiomyopathy”
We thank Dr ElBardissi for his letter and insightful commentary. In our investigation,1 there were no differences in rates of survival free of severe symptoms between surgical myectomy and septal ablation in the overall population, but patients under the age of 65 years did better with surgery. For patients who underwent septal ablation and then later required myectomy, follow-up was ceased at the time of the occurrence of severe symptoms. Analysis of the end point of severe symptoms was performed on an intention-to-treat basis, and thus patients who had myectomy after septal ablation were not grouped into the cohort of myectomy patients. We agree that patients who have myectomy after ablation have a poorer outcome, which has implications for the selection of intervention.
In all patients, septal ablation was undertaken when an appropriate septal artery could be catheterized and contrast echocardiography through the artery demonstrated enhancement of myocardium that was intimately involved in outflow tract obstruction. Analysis of the septal artery anatomy was not a primary aim of our investigation. Nonetheless, in prior studies, it has been shown that up to 20% of patients may not have an appropriate perforator artery for septal ablation.2 Whether we can prospectively identify these patients is an area of current investigation.
We agree with Dr ElBardissi that initial procedural success may be erroneously concluded because of occurrence of myocardial stunning without infarction of the targeted area. This possibility is highlighted in our article,1 which states that 12 of 113 patients who were originally thought to have short-term procedural success with septal ablation later on developed severe symptoms. Of note, there also is a subset of patients (16 of 24 patients in our study) in whom ventricular remodeling leads to further decrease in the outflow tract gradient and symptom improvement.3 Overall, we believe that septal ablation is a viable alternative therapy for patients with obstructive hypertrophic cardiomyopathy and severe symptoms. Further long-term studies on the durability of its efficacy and potential impact on the longevity of these patients still are required.
Sorajja P, Valeti U, Nishimura RA, Ommen SR, Rihal CS, Gersh BJ, Hodge DO, Schaff HV, Holmes DR Jr. Outcome of alcohol septal ablation for obstructive hypertrophic cardiomyopathy. Circulation. 2008; 118: 131–139.
Van Dockum WG, Beek AM, ten Cate FJ, ten Berg JM, Bondarenko O, Gotte MJ, Twisk JW, Hofman MB, Visser CA, van Rossum AC. Early onset and progression of left ventricular remodeling after alcohol septal ablation in hypertrophic obstructive cardiomyopathy. Circulation. 2005; 111: 2503–2508.