Acute testing of the rate-smoothed pacing algorithm for ventricular rate stabilization

We evaluated the capability of a new pacemaker-based rate-smoothing algorit hm (RSA) to reduce the irregular ventricular response of AF. RSA prevents s udden decreases in rate using a modified physiological band and flywheel fe ature. Twelve patients (51 +/- 21 years) with hemodynamically tolerated AF of 4 months to 20 years duration were studied. Atrial and ventricular leads were connected to the external pacemaker device in the electrophysiology l aboratory, Consecutive RR intervals during AF were measured at baseline and after ventricular pacing with RSA ON. Ventricular pacing with the rate smo othing algorithm reduced maximum RR intervals (1,207 +/- 299 vs 855 +/- 148 ms, P = 0.0005), with no significant change in the minimum RR interval (40 1 +/- 55 vs 393 +/- 74 ms, P = 0.292). A small shortening of the mean RR in terval (634 +/- 153 vs 594 +/- 135 ms, P = 0.007) was seen with no change i n the median RR interval (609 +/- 153 vs 595 +/- 143 ms,P = 0.388). There w as a 43% reduction in RR standard deviation (145 +/- 52 vs 82 +/- 28, P = 0 .0005), 49% reduction in mean absolute RR interval difference (MAD) (152 +/ - 64 vs 77 +/- 34, P = 0.0005) and MAD/mean RR ratio (0.23 +/- 0.05 vs 0.13 +/- 0.04, P = 0.0005). We conclude that rate-smoothed pacing effectively r educes RR variability of AF in the acute setting.