Native and Paced QRS Duration in Right Ventricular Apex Paced Patients

Background: The value between paced QRS duration (pQRSd) and native QRS duration (nQRSd) in paced population has not been compared. The relation between nQRSd and pQRSd remains undefined now. Methods and Results: A total of 310 right ventricular apex (RVA) paced patients were enrolled. The correlation coefficients between nQRSd and pQRSd to left ventricular (LV) dimensions and ejection fraction (LVEF) were calculated and then compared. The association between pQRSd and nQRSd was examined. pQRSd was better correlated with LVDD, LVDS, and LVEF than nQRSd in all patients or patients with no intraventricular conduction block (NIVCB, n = 136) or complete right bundle-branch block (CRBB, n = 86) (all P < .01). pQRSd was positively correlated with nQRSd in NIVCB. CRBB, and complete left bundle-branch block (CLBB, n = 45) patients (r = 0.408, 0.465, and 0.766, respectively; all P < .001). However, pQRSd was not different between NIVCB. CRBB, and CLBB patients (P > .05) after adjusting for LVEF and LV dimensions. Conclusions: pQRSd is superior to nQRSd in terms of reflecting LV structures and function in RVA-paced patients. Bundle branch block (BBB) has no significant effect on pQRSd and thus further studies are needed to clarify whether BBB is an independent risk factor for the development of heart failure after RVA pacing. (J Cardiac Fail 2010:16:239-245)