I read with interest the innovative procedure of percutaneous transvalvular endomyocardial cryoablation for the treatment of hypertrophic cardiomyopathy reported by Keane et al¹ in the June 2007 issue of the Journal of Invasive Cardiology. Their disappointing results are not surprising, because of the ‘blind’ nature of the procedure. Unlike the surgical transaortic myectomy which is done under direct vision² or percutaneous transluminal septal myocardial ablation which relies on the precise vascular distribution of the first septal branch of the left anterior descending coronary artery into which alcohol was injected^3,4 cryoablation of the interventricular septum is an imprecise technique, because the exact location of the septal contact by the cryo-catheter is ‘by fluoroscopic guidance’ which is far from being perfect.

It is, therefore, no surprise that there was no reduction in septal thickness on postoperative echocardiogams in all 3 of their patients. On the other hand, because the left ventricular outflow tract obstruction and therefore the systolic gradient in hypertrophic cardiomyopathy is a dynamic process, it is not surprising that the authors found occasional reduction in post-procedure systolic gradient despite unchanged septal thickness. However, the procedure is worthy of further exploration as an alternative percutaneous strategy to percutaneous transluminal septal myocardial ablation for the treatment of hypertrophic cardiomyopathy, because hypertrophic cardiomypathy is not only the most common genetic cardiovascular disease6 but also a global disease affecting a large number of patients all around the world.^7,8

Tsung O. Cheng,

MD Professor of Medicine

George Washington University

Washington, D.C. 20037

Email: tcheng@mfa.gwu.edu