IntroductionChronic 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.ObjectiveTo compare pacemaker-induced dyssynchrony among different pacing sites in
right ventricular stimulation.MethodsCross-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.ResultsForty 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<0.05) - no
difference with those electrode on the free wall. No difference was noted in
the pre-aortic ejection time (P=0.9).ConclusionApical pacing showed a lower interventricular conduction delay when compared
to medial septum site. Our findings suggest that apical pacing dyssynchrony
is not ubiquitous, as previously thought, and that it should remain an
option for lead placement.