Progressive decrease of outflow gradient and septum thickness after percutaneous alcoholization of the interventricular septum in hypertrophic obstructive cardiomyopathy

Background: The aim of this study was to evaluate the immediate- and mid-term results of percutaneous transluminal septal myocardial ablation (PTSMA) of the interventricular septum performed in 15 consecutive patients with hypertrophic obstructive cardiomyopathy between 1996 and 1999. Methods: Prior to intervention, all patients (7 males, 8 females, mean age 62 ± 11 years) complained of severe dyspnea (NYHA functional class III-IV) despite medical treatment with β-blockers and/or verapamil. Family history of hypertrophic cardiomyopathy was present in 2 cases. Dehydrated alcohol (4.8 ± 1.5 ml/pt) was selectively infused into the first septal perforator artery through over-the-wire balloon catheters. In 5 patients a second or a third septal branch was treated because the intraventricular gradient persisted above 50 mmHg after the initial alcohol infusion. Results: Alcohol infusion induced an average peak creatine phosphokinase level of 1524 ± 427 IU/l. No iterating ventricular arrhythmias occurred during the procedure or in the 2-3 days of continuous ECG monitoring after the procedure. Two patients (13%) developed a complete atrioventricular block after the procedure, requiring permanent double-chamber pacing. Electrocardiographic changes included a > 2 mm ST segment elevation and transient right bundle branch block or left anterior/left posterior hemiblock in all patients. Peak basal intraventricular gradient decreased from 80 ± 27 to 24 ± 27 mmHg (p < 0.01) during cardiac catheterization and from 81 ± 27 to 35 ± 25 mmHg (p < 0.01) at the echocardiograpic control performed during the hospital stay. At follow-up (mean 5.1 ± 3.6 months), all patients were in NYHA functional class I or II. Repeat echocardiography showed a further significant decrease in intraventricular gradient to 25 ± 26 mmHg (p < 0.01) and a progressive decrease in intraventricular septum thickness (25 ± 5 mm before treatment, 21 ± 6 mm before hospital discharge, 17 ± 3 mm at follow-up, p < 0.01). Conclusions: PTSMA of the intraventricular septum effectively relieves symptoms in selected patients with hypertrophic obstructive cardiomyopathy. The immediate decrease in intraventricular gradient is followed by a further decline at follow-up with a progressive reduction in the intraventricular septum thickness.