Prognostic Role of Complete Right Bundle Branch Block after Percutaneous Transluminal Septal Myocardial Ablation in First Series of Patients with Hypertrophic Obstructive Cardiomyopathy

Background. The siginificance of complete right bundle branch block(CRBBB) after percutaneou transluminal septal myocardial ablation(PTSMA) for treatment of hypertrophic obstructive cardiomyopathy(HOCM) still remains unclear. 47 patients with HOCM were divided into CRBBB and non-CRBBB(NBBB) groups according to their EKG changes after PTSMA. Serial EKG,resting and stress-induced echocardiographic parameters were determined within 3 years of follow-up. Primary endpoint included cardiac death and resting left ventricular outflow tract pressure gradient(LVOTG) increase by 50%. Immediately after PTSMA, there were 22 patients(42%) with CRBBB and 25 patients with NBBB. No death and complete AV block requiring permanent pacemaker. NBBB Patients had longer history of symptomatic HOCM than NBBB(13.42?4.72 vs 6.03?1.68years,p=0.10). PTSMA resulted in significant decrease in resting and stress-induced LVOTG(SLVOTG) significantly(p<0.01),the later in NBBB group was higher than that in CRBBB group beginning from 12 months later after procedure(p=0.01),and went up to 40 mmHg by the time of 36 months after PTSMA , with similar clinical symptoms`improvement to CRBBB group(no patient at NEW YORK Heart Function Class III in both groups) . Left ventricular mass decreased significantly (p<0.001)in both groups with higher degree of decrease in CRBBB group(from 418?184g to 287?96g)compared to that in NBBB group( from 387?169g to 305?107g,p<0.001) at 3 years of follow-up. There were negative relationship between reduction of LVOTG and peak plasma level of plasma CK-MB(r=0.63,p=0.01) after PTSMA and positive correlation between the peak plasma level of plasma CK-MB but rather the volume of ethanol administered and QRS duration(r=0.60,p=0.01)."LVOTG rebounding" phenomenon found in CRBBB patients was not noted in NBBB groups during PTSMA procedure. PTSMA was safe and feasible for treatment of HOCM. The patients in CRBBB group had a trend to have better long-term prognosis than in NBBB group.Further study was needed to confirm.