Effects of different atrioventricular intervals during dual-site right atrial pacing on left atrial mechanical function

Recent studies have suggested that dual-site right atrial (RA) pacing via t he high RA and coronary sinus ostium (CSos) prevents atrial fibrillation (A F). However, the programming of the atrioventricular (AV) interval associat ed with optimal left atrial (LA) mechanical function during high RA and dua l-site RA pacing has not been defined. LA mechanical function was studied b y measuring transmitral pulsed Doppler echocardiographic peak A wave veloci ty and percent A wave filling, in six women and three men, 67 +/- 8 years o f age, who had received dual-site RA pacemakers in a randomized study. Seri al echocardiographic measurements were performed during high RA or dual-sit e RA pacing at 80 beats/min with AV intervals of 50, 100, 150, or 200 ms te sted in random order. High RA and dual-site RA pacing at an AV interval of 50 ms were associated with significantly lower peak A wave velocity and per cent A wave filling compared to the other AV intervals (all P < 0.05). Comp ared with high RA pacing, dual-site RA pacing was associated with significa ntly higher peak A wave velocity (85 +/- 12 vs 72 +/- 17 cm/s, P = 0.04) an d percent A wave filling (24 +/- 3 vs 20 +/- 4 %, P = 0.02) at an AV interv al of 200 ms, but a lower peak A wave velocity at an AV interval of 200 ms (77 +/- 10 vs 84 +/- 8 cm/s, P = 0.004). In conclusion, variations in the A V interval during atrial pacing have significant effects on LA function. As a consequence of altered atrial activation, the AV interval associated wit h optimal LA mechanical function during dual-site RA pacing was significant ly shorter than that during RA pacing. This observation has important impli cations with respect to the programming of dual-site RA pacemakers implante d to prevent AF for hemodynamic purpose.