In percutaneous transluminal septal myocardial ablation for hypertrophic obstructive cardiomyopathy, it is not the speed of intracoronary alcohol injection but the amount of alcohol injected that determines the resultant infarct size.

Ablation for Hypertrophic Obstructive Cardiomyopathy, It Is Not the Speed of Intracoronary Alcohol Injection But the Amount of Alcohol Injected That Determines the Resultant Infarct Size To the Editor: In the Clinician Update on percutaneous transluminal septal myocardial ablation (PTSMA) for hypertrophic obstructive cardiomyopathy (HOCM), Kimmelstiel and Maron1 presented a successfully treated patient with maintenance of benefit 6 months later. The authors emphasized the importance of using smaller amounts of alcohol and injecting it more slowly into the first septal branch of the left anterior descending coronary artery to create more limited areas of myocardial infarction. According to the experimental study reported recently by my colleagues in China and me,2 the size of the iatrogenic myocardial infarct is directly related to the amount of intracoronary alcohol injection during PTSMA but has no relation to its speed of injection. This study was carried out in piglets. It found significant differences in myocardial infarct size with different amounts of alcohol injected but no apparent differences in myocardial infarct size with different speeds of alcohol injection. These findings have obvious clinical implications, because it is much simpler to control the amount than the speed of intracoronary alcohol injections in the cardiac catheterization laboratory. As Kimmelstiel and Maron1 mentioned, PTSMA is a promising therapeutic modality for HOCM. But they also underscored that, even in experienced hands, PTSMA may incur morbidity and mortality. Therefore, knowledge that the amount, rather than the speed, of intracoronary alcohol injection determines the size of the induced myocardial infarction (and therefore indirectly the morbidity and mortality of the procedure) should help guide the interventionists in the cardiac catheterization laboratories. According to Kimmelstiel and Maron,1 there have been an estimated 3000 PTSMA procedures performed worldwide in the last 5 years. In China, 119 patients with HOCM were successfully treated in one center,3 and 400 PTSMA procedures have now been performed without any mortality (Zhang WW, Li ZQ, personal communication). Considering that the first case of HOCM in China was diagnosed in 1973,4 China certainly has made great progress in this field in the past three decades.5