PREVENTION OF ATRIAL ARRHYTHMIAS DURING DDD PACING BY ATRIAL OVERDRIVE

We evaluated the effect of atrial overdrive on the incidence of atrial arrhythmias (AA) in 22 patients (67 +/- 9 years, 7 women, 15 men) wit h Chorus 6234 DDD pacemakers. Atrial overdrive was defined as a progra mmed paced rate 10 ppm faster than the mean ventricular rate stored fo r the last 24-hour period in the pacemaker memory. The protocol consis ted of three phases of 1 month each. Phase I: observation after discon tinuation of antiarrhythmic therapy. Phase II: arrhythmia analysis usi ng the pacemaker memory after programming the lower rate to 55 ppm. Th e fallback function and histogram data were used to document the numbe r and maximal duration of AA episodes as well as the total AA time in a month. Phase III: atrial overdrive. The mean ventricular heart rate was 65 +/- 4 beats/min before atrial overdrive versus 75 +/- 5 with at rial overdrive (P = 0.02). At the end of phase II, all patients presen ted with AA episodes (mean number per patient: 42 +/- 78 in one month) . In phase III (with atrial overdrive), 14 (64.6%) patients had no rec orded AA (group A). In the other eight patients with persistent AA epi sodes in phase III (group B), there was a significant reduction in the number of AA episodes (90 +/- 106 in phase II vs 38 +/- 87 in phase I II; P = 0.01), their total duration (166 +/- 115 in phase II vs 92 +/- 134 hours in phase III; P = 0.03) and their maximal duration (121 +/- 103 in phase II vs 85 +/- 89 min; P = 0.04). Our short-term data sugg est that atrial overdrive prevents or reduces AA episodes and demonstr ate the feasibility and need of longterm studies to determine whether this benefit is sustained.