Publication

Abstract : SIGNIFICANT VENTRICULAR DYSSYNCHRONY manifested by left bundle-branch block (LBBB) and wide QRS complex is demonstrated on an electrocardiogram (ECG) in 30% of patients with heart failure. 1 Left ventricular (LV) dyssynchrony causes decreased ventricular filling and impaired LV contractility and is associated with increased mortality. 2 In the past decade, cardiac resynchronization therapy (CRT), achieved by simultaneous LV and right ventricular (RV) pacing, has emerged as a potent therapeutic option that improves the quality of life and functional status of patients with congestive heart failure, as well as prolongs survival. 3 , 4 The goal of CRT is pacing the left ventricle at the latest activation site so that the left ventricle contracts in a synchronized manner, allowing ventricular ejection to occur before relaxation of the septum; this decreases mitral valve regurgitation (MR), increases the stroke volume, and decreases end-diastolic volume (EDV). By resynchronizing atrioventricular contraction, normal mitral valve timing is restored, and MR is reduced or eliminated. 5 In the Multicenter In Sync Randomized Clinical Evaluation (MIRACLE) trial, CRT was associated with reverse remodeling, reduced EDV, reduced end-systolic volume (ESV), reduced LV mass, increased ejection fraction (EF), reduced MR, and improved myocardial performance index. 6