Short atrioventricular delay reduces the degree of mitral regurgitation in patients with a sequential dual-chamber pacemaker.

This study was performed in a population of sequential dual-chamber pacemaker-patients with isolated mitral regurgitation (MR) to identify the "ideal atrioventricular (AV) delay" and to determine the effect of sequential pacing with the ideal AV delay on MR degree. Twenty consecutive patients (age 69 +/- 7 years; 45% men) hospitalized at our institution for symptomatic III degree AV block and isolated MR were studied. All received a dual-chamber pacemaker programmed in DDD at a rate of 70 pulses/minute. The ideal AV delay was selected using echo-color Doppler parameters; it was defined as that resulting in a lower degree of MR and in the highest cardiac output. The mean "optimal short" AV delay resulted in 98 +/- 7 ms. At short AV delay we observed a significant reduction in MR severity (regurgitant fraction from 48 +/- 12% to 25 +/- 10% and jet area from 15 +/- 2 to 9 +/- 2 cm2; p <0.0001) together with an increase in stroke volume (68 +/- 16 vs 88 +/- 15 ml; p = 0.007) and mitral early-to-late peak velocity ratio (0.79 +/- 0.33 vs 1.38 +/- 0.37; p <0.0001). In conclusion, a short AV delay may be used to improve cardiac output in sequential paced patients with pure, isolated MR.