The second-largest long-term study of ASA was a recent report on 952 German patients with a minimum 6-year follow-up. The estimated 5-, 10-, and 15-year survival rates were 95.8%, 88.3%, and 79.7%, respectively. Estimated survival free of cardiac events was 98.9% at 5 years, 97.0% at 10 years, and 96.5% at 15 years. About 5% of patients received an implantable cardioverter defibrillator.
The investigators concluded, “In this study, PTSMA [percutaneous transluminal septal myocardial ablation] could be proofed as a safe procedure with ongoing symptomatic improvement and excellent long-term survival. Therefore, PTSMA is a reasonable alternative to surgical myectomy in HOCM.” (J Am Coll Cardiol. 2018 Dec 18;72[24]:3087-94) It’s way too early in the ACC/AHA guideline revision process to say what the new recommendations will be, according to Dr. Sorajja.
One unsettled issue, in his view, is whether ASA outcomes are significantly better in high-volume centers. A study of all 11,248 patients who underwent surgical myectomy of ASA during 2003-2011 in a large U.S. inpatient database concluded that undergoing surgical myectomy in a bottom-tertile-volume hospital was independently associated with an adjusted 210% increased risk of inpatient all-cause mortality and a 280% increased risk of bleeding, but that being in the lowest tertile of ASA hospital volume wasn’t independently associated with increased risk after adjustment for potential confounders (JAMA Cardiol. 2016 Jun 1;1:[3]:324-32).
However, Dr. Sorajja indicated he didn’t find the statistically adjusted results in the ASA cohort persuasive.
“I will tell you that the favorable results in the long-term studies came from hospitals in the highest-volume tertile,” the cardiologist said.
At present, he considers surgical myectomy the gold standard therapy. With well-selected patients for ASA – that is, those for whom imaging has identified an appropriate septal artery for delivery of the alcohol, along with no more than 24 mm of septal hypertrophy so the alcohol dose can be limited to a maximum of 20-25 cc – it’s reasonable to expect gradient relief in more than 90% of patients, surgical-like results with optimal relief of left ventricular outflow tract obstruction and a residual gradient of less than 10 mm Hg in about 75%, and a procedural mortality of about 1%, he said.
Dr. Sorajja reported receiving research funding from Abbott Structural, Boston Scientific, Edwards Lifesciences, and Medtronic, and serving as a consultant to those companies and several others.