The objective of this study was to compare the optimal atrioventricular delay (OAVD) paced from right ventricular outflow tract (RVOT) with that paced from right ventricular apex (RVA) in patients implanted with DDD pacemaker. A total of 43 patients implanted with DDD pacemaker due to high or third degree atrioventricular block were enrolled. The atrial lead was positioned in the right atrial appendage and the ventricular lead was randomly placed in RVOT (n=21) or RVA (n=22). AVD optimization increased aortic flow velocity integral both in RVOT and RVA paced patients. P wave duration (P<0.05) rather than QRS duration (P>0.10) was the independent determinant of OAVD. OAVD was similar between RVA and RVOT paced patients (116.81 +/- 34.00 ms vs 107.14 +/- 26.30 ms, P>0.05). (C) 2008 Elsevier Ireland Ltd. All rights reserved.