Effects of Long-Term Biventricular Stimulation for Resynchronization on Echocardiographic Measures of Remodeling. - VIGOR Echo substudy
Assess changes in left ventricular (LV) performance and remodeling attributable to biventricular pacing (BVP) in patients with dilated cardiomyopathy.
Echocardiograms were performed at baseline 6, 12 and 18 weeks after implantation of a BVP device, which involved endocardial right atrial and right ventricular leads but an epicardial LV lead. For the first 6-weeks, patients were randomized to active BVP or no pacing, after which all patients had active BVP for the remaining 12 weeks. Echocardiographic parameters included LV dimensions and volumes in diastole and systole, ejection fraction (EF) and velocity time integral (VTI) of the aortic valve (AV) and left ventricular outflow tract (LVOT) as well the myocardial performance index (MPI).
During the six week randomization trial there were no significant changes in LV size or function with the exception of an improved AV-VTI in the BVP group. After 12 weeks of continuous BVP, there was a reduction in LA size, LV diastolic and systolic volumes and dimensions but no changes in sphericity index. LVOT VTI increased from 15.5 + 5 to 17.2 + 4 (p = 0.01) and MPI decreased from 0.77 + 0.3 to 0.62 + 0.2 (p = 0.002). Mitral regurgitation grade decreased from 1.5 + 0.7 to 1.2 + 0.7 (p = 0.02). The only measure of diastolic function which changed was mitral deceleration time (144 + 53 v. 171 + 67 ms, p = 0.01).
Among patients with dilated cardiomyopathy, BVP results in resynchronization of LV contraction as well as a reversal of chamber dilation and improvement in systolic function. This study demonstrates a potential mechanism by which BVP may improve symptomatic status. The authors demonstrate a reversal of chamber dilation in patients with dilated cardiomyopathy and the subsequent improvement in contractile performance. It is notable that after 12 weeks of BVP, the favorable changes in size and performance persisted after short-term discontinuation of BVP, suggesting that this therapy results in persistent changes in ventricular geometry and is not an acute hemodynamic effect. The patients enrolled in this study are somewhat different from many patients with congestive heart failure in that the severity of mitral regurgitation was relatively mild and severe diastolic dysfunction was infrequent.
Saxon LA, DeMarco T, Schafer J, Chatterjee K, Kumar UN, Foster E for the VIGOR Congestive Heart Failure Investigators. Effects of Long-Term Biventricular Stimulation for Resynchronization on Echocardiographic Measures of Remodeling. Circulation. 2002;105:1304-10.
Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Valvular Heart Disease, Implantable Devices, Acute Heart Failure, Echocardiography/Ultrasound, Mitral Regurgitation
Keywords: Mitral Valve Insufficiency, Human Rights, Heart Failure, Diastole, Heart Ventricles, Systole, Hemodynamics, Cardiomyopathy, Dilated, Cardiac Resynchronization Therapy, Deceleration, Echocardiography
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