Percutaneous Transluminal Septal Myocardial Ablation In Hypertrophic Obstructive Cardiomyopathy: Short-term Results And Predictors Of Acute Complete Atrioventricular Block

Background:Hypertrophic obstructive cardiomyopathy (HOCM) is a special type of hypertrophic cardiomyopathy, which was named by asymmetric septal hypertrophy and left ventricular outflow tract (left ventricle outflow tract, LVOT) obstruction. It may manifested as palpitations, chest pain, exertion dyspnea, dizziness, syncope, some patients lead to heart failure and sudden death in clinical. The treatment of percutaneous transluminal septal myocardial ablation (PTSMA) on HOCM is a new progress of interventional cardiology in recent years. By means of alcohol-induced occlusion of a septal branch, it relieve outflow tract obstruction improve cardiac function, improve the clinical symptoms, and improve exercise tolerance.Acute complete heart block(ACHB) was defined as complete atrioventricular block occurring at least 10s during the PTSMA procedure.Objective:In this study, the short-term results of PTSMA in 70 patients was observed, including left ventricular outflow tract gradient (LVOTG) before and immediately after catheter ablation by catheter, left ventricular outflow tract width (LVOTW), LVOTG, interventricular septal (IVS) thickness, and left ventricular ejection fraction (LVEF) before and after ablation by echocardiography, and analysed the predictors of ACHB.Materials and Methods:Seventy patients with drug-refractory accepted PTSMA (Sigwart way) from January 2004 to December 2007 in this study. We measured the resting and stimulated LVOTG before and immediately after PTSMA by dual-channel pressure method, used echocardiography to detect the left ventricular outflow tract width, septal thickness, LVOTG at rest, and ejection fraction of these Patients before PTSMA and after two week, and tested them using the Student t test, ablation of vascular, alcohol consumption, and ECG were recorded and the complications were observed during and after ablation. Parameters which were significantly correlated with ACHB were entered stepwise in one multivariate logistic regression model to analyze the predictive power of each parameter.Results:One patient died of pericardial tamponade after occluder,one patient occured acute anterior wall myocardial infarction after PTSMA, eight patients appeared ACHB, one of them did not restore seven days after PTSMA and implanted permanent cardiac pacemaker, and three patients werenot successful, one of them occurred transient complete atrio-ventricular block, and two of them occurred ventricular tachycardia. The invasively determined LVOTG could be reduced from 79.37±32.87 mmHg to 17.51±14.53 mmHg at rest (p<0.0001) and from 104.67±50.84 mmHg to 32.83±25.78 mmHg after extrasystole (p<0.001). Two weeks later, we also observed the reduction of LVOTG by echocardiography. Other parameters didnot appear obviously changes NYHA functional class improved from 2.8±0.6 before ablation to 1.9±0.5 two weeks after ablation(p<0.001). On univariate regression analysis predictors of ACHB, include female gender(p <0.001), advanced age (p=0.045), LVOTG at rest (p=0.04), and pre-existing LBBB (p=0.004). On multivariate analysis found that pre-existing LBBB and advanced age were the predictors of ACHB (p<0.05 for all).Conclusions:PTSMA can significantly reduce LVOTG, extenuate obstruction and improve clinical symptoms, and it has a satisfactory short- term effieacy in the treatment of HOCM. A pre-existing LBBB and advanced age were risk factors for ACHB.