Impact Of Myocardial Scar On Ventricular Electrical And Left Ventricular Mechanical Dyssynchrony In Nonischemic Cardiomyopathy Patients

BACKGROUNDS: Epidemiology studies show that the morbidity of chronic heart failure was 0.4-2%. Various heart diseases(e.g. ischemic cardiomyopathy,dialated cardiomyopathy, hypertensive heart disease, valvular heart disease etc) could alter the cardiac structure and function,and ultimately induce heart failure. Although great progress of drug treatment is obtained, mortality is still high. During the two decades,CRT has been a useful method for treating chronic heart failure. During the heart failure remodeling progress, myocardial fibrosis is a compensation mechanism as initial, while ultimately results in cardiac tissue stiffness and damags the cardiac function. Myocardial scar of heart failure, especially after myocardial infarction, is clear. For nonischemic cardiomyopathy fibrosis, it is poorly understood, while did existed. Myocardial fibrosis and scar may have an impact on cardiac electrical activity. Among heart failure patients, the proportion of QRS duration prolonged is presented almost in 40%, indicating electrical dyssynchrony. Meanwhile, some patients has mechanical dyssynchrony.OBJECTIVES: The aim of this study was to assess the correlation of left ventricular myocardial scar to ventricular electrical and left ventricular mechanical dyssynchrony of nonischemic heart failure patients.METHODS: 99 nonischemic heart failure patients were involved in. Clinical data were collected and analysed. SPECT-MPI resting nuclide analysed the severity of left ventricular scar burden and mechanical dissynchrony by phase analysis method.QRS duration and morphology were simultaneously measured by body surfaceelectrocardiogram. Grouped according to QRS morphology, patients were separated into 4 groups: LBBB(left bundle branch block)group(n=51), RBBB(right bundle branch block)group(n=6), IVCD(Intraventricular conduction delay)group(n=11),NORMAL(normal QRS duration) group(n=31). Correlation between scar burden and QRS duration 、 mechanical dyssynchrony were analysed. Simultaneously,correlation between scar burden and cardiac electrical(QRS duration)、mechanical dyssynchrony activity(phase and bandwidth) were assessed by linear correlation on four subgroups.Considering different factors may influence the QRS duration and mechanical dissynchrony, several factors were measured by multiple regression analysis.RESULTS: Myocardial scar burden had positive correlation with QRS duration(P=0.04, r2=0.04). Myocardial scar burden had positive correlation with phase(P=0.017, r2=0.57) and bandwidth(P=0.023, r2=0.052).The correlation between myocardial scar burden and QRS duration of different QRS morphologies myocardial scar:For four QRS morphologies(LBBB RBBB IVCD and normal QRS morphology), there was no correlation between myocardial scar burden and QRS duration(LBBB,P=0.625;RBBB,P=0.052;IVCD,P=0.78;NORMAL,P=0.124)。The correlation between myocardial scar burden and myocardial mechanical dyssynchrony of different QRS morphologies myocardial scar:For three QRS morphologies(LBBB IVCDand normal QRS morphology), there was no correlation between myocardial scar burden and myocardial mechanical dyssynchrony(phase correlation: LBBB, P=0.14; IVCD P=0.85; NORMAL P=0.83; bandwidth correlation: LBBB P=0.15; IVCD P=0.92; NORMAL P=0.74).For RBBB morphology, myocardial scar burden had correlation with myocardial mechanical dyssynchrony(phase correlation: RBBB, P=0.02; bandwidth correlation: RBBB,P=0.03).CONCLUSIONS: In nonischemic heart failure patients, the heavier scar burden left ventricular had, the more ratio of bundle branch block.In nonischemic heart failure patients, scar burden had minor impact on cardiac electrical and mechanical activity.