Analysis of Dyssynchrony and Ventricular Function in Right Univentricular Stimulation at Different Positions

Abstract Introduction: Chronic stimulation of the right ventricle with pacemaker is associated with ventricular dyssynchrony and loss of contractility, even in subjects without previous dysfunction. In these patients, there is a debate of which pacing site is less associated with loss of ventricular function. Objective: To compare pacemaker-induced dyssynchrony among different pacing sites in right ventricular stimulation. Methods: Cross-sectional study of outpatients with right ventricle stimulation higher than 80% and preserved left ventricular ejection fraction. Pacing lead position (apical, medial septum or free wall) was assessed through chest X-rays. Every patient underwent echocardiogram to evaluate for dyssynchrony according to CARE-HF criteria: aortic pre-ejection time, interventricular delay and septum/posterior wall delay on M mode. Results: Forty patients were included. Fifty-two percent had apical electrode position, 42% mid septum and 6% free wall. Mean QRS time 148.97±15.52 milliseconds. A weak correlation between the mean QRS width and pre-aortic ejection time (r=0.32; P=0.04) was found. No difference in QRS width among the positions could be noted. Intraventricular delay was lower in apical patients against mid septal (34.4±17.2 vs. 54.3±19.1 P