Impact of Different Right Ventricular Lead Positions on QRS Complex Duration Post Cardiac Resynchronization Therapy Device Implantation and its effect on clinical response

Abstract

Cardiac resynchronization therapy (CRT) is one of the most important therapeutic advancements in recent years for patients with heart failure with reduced ejection fraction (HFrEF). Throughout the past two decades, numerous trials and studies have repeatedly illustrated the efficacy of CRT to improve outcomes in carefully selected patients by eliminating the dyssynchrony which results from bundle branch block activation and restore the mechano-energetic efficiency of the heart. During CRT, both the left and right ventricles are stimulated in an attempt to re-coordinate cardiac electrical activation and produce a synchronous and efficient contraction. However, 20% to 40% of patients are non-responders to CRT therapy. Several variables, including cause of HF, pattern of mechanical dyssynchrony, and site of LV pacing, have been investigated as predictors of response. Whether the right ventricular (RV) lead position may improve the response to CRT is a matter of debate. Apical position is conventional, especially in patients receiving a CRT-defibrillator (CRT-D) but long-term RV apical pacing may adversely affect cardiac function in intracardiac cardioverter defibrillator (ICD) recipients. Alternative RV pacing sites, mainly RV septal, have been recently proposed in CRT recipients. We have studied the impact of different RV lead positions (apical versus septal) on QRS complex duration and the clinical response (NYHA functional class), we also evaluated the relationship between change of QRS complex duration and the improvement of clinical response, the study enrolled 100 patients presented for routine follow up and programming in electrophysiology clinic of Ain shams university hospitals. The patients divided into two groups, RV apex (RVA)group (n 54) and RV septum (RVS) group (n 46).