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 injected3,4 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
1. Keane D, Hynes B, King G, Shiels P, Brown A. Feasibility study of percutaneous transvalvular endomyocardial cryoablation for the treatment of hypertrophic obstructive cardiomyopathy. J Invasive Cardiol 2007;19:247-251.
2. Morrow AG, Lambrew CT, Braunwald E. Idiopathic hypertrophic subaortic stenosis: II. Operative treatment and the results of pre- and postoperative hemodynamic evaluation. Circulation 1964;30(Suppl 4): 120-151.
3. Sigwart U. Non-surgical myocardial reduction for hypertrophic obstructive cardiomyopathy. Lancet 1995;346:211-214.
4. Li ZQ, Cheng TO, Zhang WW, Qiao SB, Zhao LY, Jin YZ, Guan RM, Liu L. Percutaneous transluminal septal myocardial ablation for hypertrophic obstructive cardiomyopathy. The Chinese experience in 119 patients from a single center. Int J Cardiol 2004;93:197-202.
5. Cheng TO. Percutaneous versus surgical treatment of hypertrophic obstructive cardiomyopathy: the pendulum continues to swing. J Methodist DeBakey Heart Center 2005;1(4):2.
6. Maron BJ. Hypertrophic cardiomyopathy. A systematic review. JAMA 2002;287:1308-1320.
7. Maron BJ. Hypertrophic cardiomyopathy: an important global disease. Am J Med 2004;116:63-66.
8. Cheng TO. Hypertrophic cardiomyopathy is a global disease including China. Int J Cardiol, in press.