This study was conducted to assess outcomes after percutaneous transluminal septal myocardial ablation (PTSMA) treatment in 131 patients (mean age 56 +/- 16 years) with obstructive hypertrophic cardiomyopathy. In-hospital and follow-up complications as well as late PTSMA failure (defined as unsatisfactory clinical outcome and a significant residual outflow tract gradient, necessitating reintervention) were noted. Baseline clinical, echocardiographic, and PTSMA characteristics were examined as determinants of outcomes. Also, the effect of ethanol volume and the role of a learning curve were investigated. PTSMA was successful in 90% of the patients. In-hospital and follow-up cardiac events were noted in 20 patients, including cardiac death (in-hospital n=4, follow-up n=1), acute myocardial infarction due to ethanol leakage (n=1), coronary dissection (n=2), nonfatal cardiac tamponade (n=1), and permanent pacemaker (n=6) or cardiac defibrillator (in-hospital n=4, follow-up n=1) implantation. Late PTSMA failure was noted in 12 patients. All baseline characteristics were comparable between successful and failed PTSMA. Ethanol volume was related to peak creatinine kinase value (p < 0.0001) but not to late PTSMA failure or greater need for pacemaker implantation. Late PTSMA failure occurred more frequently in PTSMA procedures performed in the early, less experienced time period (p < 0.001). In conclusion, this study confirms that PTSMA, although effective, has a relatively high complication rate. Late PTSMA failure could not be predicted by baseline characteristics but could partially be explained by a learning-curve effect. This finding implies that PTSMA procedures should be restricted to experienced centers. (c) 2008 Elsevier Inc. All rights reserved.