0446: Septal right ventricular lead positioning and optimized DDD pacing versus intrinsic conduction in sinus node disease: an echocardiographic study. The optimist trial

Introduction Preserved intrinsic conduction in paced sinus node disease (SND) patients seems to be associated with a better outcome when compared with apical right ventricular (RV) DDD pacing.The prospective, multicenter, randomized OPTIMIST study was designed to compare RV lead positioning in the septum to preserved intrinsic conduction in chronically paced SND patients. Methods SND patients with a class I indication were implanted with a DDD pacemaker (St. Jude medical), the RV lead being located in the midseptum. The algorithm VIP™ (Ventricular Intrinsic Preference) was programmed « on » in all patients at hospital discharge. After a 6 weeks observational period, patients with a ventricular pacing percentage inferior to 10% were randomized in 2 parallel groups: VIP « on » (preserved natural conduction - group 1) or « off » with AV delay optimization (RV pacing - group 2). Patients were followed every 6 months with echocardiography through 18 months. The primary endpoint was the left ventricular end-systolic diameter (LVESD) (Corelab analysis), with a non inferiority hypothesis. Results 216 patients mean age 76.07±9.45 were included and 167 randomized. The baseline characteristics were comparable in group 1 and 2 including left ventricular ejection fraction, LVEF (62.4±12.6 vs 64.4±8.7%), LVESD (32.7±8.5 vs 32.5±9.3mm) and 6 weeks RV pacing percentage (1.81±1.92 vs 2.15±2.07%). At the end of FU, as expected the percentage of RV pacing was significantly higher in group 2 (78.9±31.6 vs 7.9±17.4%). The LVEF was 62.3±10.1% in group 1 and 60.9±10.9% in group 2 (NS) and the LVESD was 31.9±7.23mm in group 1 and 31.26±7.21mm in group 2 (NS).The non-inferiority hypothesis was validated (p=2.572e-06 for a delta = 4.785). AF burden was not different between the 2 groups. Conclusion When implanting the RV lead in the midseptum, DDD pacing with high percentage of RV capture was not associated with LV echocardiographic deterioration as compared to preserved intrinsic conduction pacing mode. January 17 th , Saturday 2015