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

Recent studies have suggested that dual-site right atrial (RA) pacing via the high RA and coronary sinus ostium (CSos) prevents atrial fibrillation (AF). However, the programming of the atrioventricular (AV) interval associated with optimal left atrial (LA) mechanical function during high RA and dual-site RA pacing has not been defined. LA mechanical function was studied by measuring transmitral pulsed Doppler echocardiographic peak A wave velocity and percent A wave filling, in six women and three men, 67 +/- 8 years of age, who had received dual-site RA pacemakers in a randomized study. Serial echocardiographic measurements were performed during high RA or dual-site RA pacing at 80 beats/min with AV intervals of 50, 100, 150, or 200 ms tested 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 percent A wave filling, compared to the other AV intervals (all P < 0.05). Compared with high RA pacing, dual-site RA pacing was associated with significantly higher peak A wave velocity (85 +/- 12 vs 72 +/- 17 cm/s, P = 0.04) and percent A wave filling (24 +/- 3 vs 20 +/- 4%, P = 0.02) at an AV interval of 100 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 AV interval during atrial pacing have significant effects on LA function. As a consequence of altered atrial activation, the AV interval associated with optimal LA mechanical function during dual-site RA pacing was significantly shorter than that during RA pacing. This observation has important implications with respect to the programming of dual-site RA pacemakers implanted to prevent AF for hemodynamic purpose.