Functional abnormalities in patients with permanent right ventricular pacing: The effect of sites of electrical stimulation

Abstract

OBJECTIVES: We sought to evaluate the long-term effects of alternative right ventricular pacing sites on myocardial function and perfusion. BACKGROUND: Previous studies have demonstrated that asynchronous ventricular activation due to right ventricular apical (RVA) pacing alters regional myocardial perfusion and functions. METHODS: We randomized 24 patients with complete atrioventricular block to undergo permanent ventricular stimulation either at the RVA (n = 12) or right ventricular outflow (RVOT) (n = 12). All patients underwent dipyridamole thallium myocardial scintigraphy and radionuclide ventriculography at 6 and 18 months after pacemaker implantation. RESULTS; After pacing, the mean QRS duration was significantly longer during RVA pacing than during RVOT pacing (151 ± 6 vs. 134 ± 4 ms, p = 0.03). At six months, the incidence of myocardial perfusion defects (50% vs. 25%) and regional wall motion abnormalities (42% vs. 25%) and the left ventricular ejection fraction (LVEF) (55 ± 3% vs. 55 ± 1%) were similar during RVA pacing and RVOT pacing (p > 0.05). However, at 18 months, the incidence of myocardial perfusion defects (83% vs. 33%) and regional wall motion abnormalities (75% vs. 33%) were higher and LVEF (47 ± 3 vs. 56 ± 1%) was lower during RVA pacing than during RVOT pacing (all p < 0.05). Patients with RVA pacing had a significant increase in the incidence of myocardial perfusion defects (p < 0.05) and a decrease in LVEF (p < 0.01) between 6 and 18 months, but patients with RVOT pacing did not (p > 0.05). CONCLUSIONS: This study demonstrates that preserved synchronous ventricular activation with RVOT pacing prevents the long-term deleterious effects of RVA pacing on myocardial perfusion and function in patients implanted with a permanent © 2002 by the American College of Cardiology Foundation.