Percutaneous transluminal septal myocardial ablation in hypertrophic obstructive cardiomyopathy: acute results in 66 patients with respect to myocardial contrast echocardiography

Background: In hypertrophic obstructive cardiomyopathy (HOCM) therapy, surgical myectomy and DDD pacemaker implantation are considered to be established extensions to medical treatment. As an alternative procedure for reducing the left ventricular outflow tract gradient (LVOTG), percutaneous transluminal septal myocardial ablation (PTSMA) by alcohol-induced septal branch occlusion has been introduced. We report on the acute results and the short-term clinical course following 66 PTSMA interventions in symptomatic patients (pts.) with HOCM. Methods: In pts. who were symptomatic despite adequate drug therapy (31 women, 35 men; mean age 52.9 +/- 15.0 years, range: 16-86) 66 PTSMA interventions were performed (4 pts. with a re-intervention). Septal branches were occluded by injection of 3.5 +/- 1.8 (1.5-11.0) ml ethanol (96 %). In the first 30 pts. the target vessel was determined by probatory balloon occlusion (PBO) alone, in the following 36 by additional myocardial contrast echocardiography (MCE). In-hospital followup of LVOTG and clinical course were determined. Results: The invasively determined LVOTG could be reduced by > 50 % or eliminated in 54 interventions (82 %) with a mean reduction from 71.2 +/- 34.4 (4-174) to 18.0 +/- 21.5 (0-105) mm Hg at rest and from 145.7 +/- 42.3 (68-257) to 63.7 +/- 49.3 (0-185) mm Hg post extrasystole (p < 0.0001). All pts. experienced angina pectoris within the first 24 hours. The creatine kinase peak was 690 +/- 364 (201-1810) U/l after 11.0 +/- 5.4 (4-24) hours. 45 pts. (68 %) developed trifascicular block, requiring temporary, or in 9 cases (14 %) permanent, (DDD) pacemaker implantation. Two pts. (3 %) died 9 and 2 days after a successful intervention, due to uncontrollable ventricular fibrillation associated with betasympathomimetic and theophylline treatment for chronic obstructive pulmonary disease in one case, and fulminant pulmonary embolism in the other. The remaining pts. were discharged after 11.1 +/- 4.6 (5-24) days, following an uncomplicated hospital course. The introduction of MCE was associated with a higher percentage of short-term success (92 % vs. 70 %, p < 0.015). Conclusions: PTSMA in HOCM is a promising non-surgical technique for septal myocardial reduction with a consecutive reduction of the LVOTG. MCE has shown to be a useful addition to PBO for selection of the target vessel. Possible complications are trifascicular blocks requiring permanent pacemaker implantation and tachycardiac rhythm disturbances. Prospective, long-term observations of larger populations and a comparison with the established forms of therapy are necessary in order to determine the definitive significance of PTSMA.