Dual-chamber pacing systems with sensor-based rate-adaptive capability (DDDR pacemakers) provide paced patients with the potential benefits of both a reliable chronotropic response and maintenance of atrioventricular (AV) synchrony. However, there is concern that clinical and programming complexities may necessitate frequent reprogramming of pacemakers from the DDDR mode to less physiologic pacing modes (in particular VVI or VVIR). Consequently, this study assessed the stability of pacing-mode programming, and the factors affecting pacing-mode selection in patients with a DDDR-capable pacing system. Clinical status during follow-up (18.2 ± 6.7 months) was assessed in 75 patients. Principal diagnoses providing an indication for pacing were: (1) AV block alone, 18 of 75 patients (24%); (2) sick sinus syndrome alone, 41 (55%); and (3) combined AV block and sick sinus syndrome, 16 (21%). Twenty-three patients had history of atrial tachyarrhythmias. At implantation, 66 devices (88%) were programmed to DDDR mode, 7 (9%) to DDD, and 2 (3%) to DVIR. At last follow-up, the respective distribution of programmed modes was 83% DDDR, 10% DDD, 4% DVIR and 3% VVIR. During the study, the initial pacing mode remained unchanged in 54 patients (72%) and needed modification in 21 (28%). Of the latter 21 patients, atrial tachycardia was the basis for a programming change in 11 (52%), of whom 8 had history of atrial tachycardias. In general, postimplant atrial arrhythmia occurrences proved controllable, and ultimately return to a rate-adaptive dualchamber pacing mode (DDDR, DDD or DVIR) was achieved in most cases. The remaining reprogrammings were primarily to optimize hemodynamic benefit. Consequently, although reprogramming may be needed (28% of patients in this study), especially in patients with history of atrial tachyarrhythmias, the flexibility provided by DDDR-capable pacing systems enabled maintenance of dual-chamber rate-adaptive pacing in most patients during follow-up.
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From the Department of Medicine (Cardiovascular Division), University of Minnesota Medical School, Minneapolis, Minnesota; St. Joseph’s Heart Institute, Tampa, Florida; Iowa Heart Center, Des Moines, Iowa; Baylor University Medical Center, Dallas, Texas; and Cardiovascular Consultants, Kansas City, Missouri. This study was supported by a grant from the Electrophysiology Research Fund, Minnesota Regional Health Associates Foundation, Minneapolis, Minnesota. Manuscript received August 3, 1992; revised manuscript received and accepted October 1, 1992. Address reprints: David G. Benditt, MD, Cardiovascular sion, University of Minnesota Medical School, Box 341, UMHC, neapolis, Minnesota 55455.