The aim of this study was to compare DDD and dual sensor VVIR (activity and QT) pacing modes in complete AV block (CAVB). Eighteen patients (14 men and 4 women, aged 70 +/- 6.5 years) implanted with a dual chamber, dual sensor pacemaker for CAVB with normal sinus node chronotropic function were studied. A quality-of-life and cardiovascular symptom questionnaire, and a treadmill exercise test were completed after a period of VVIR and a period of DDD pacing, each lasting 1 month. Overall quality-of-life and cardiovascular symptoms did not significantly differ, though three patients felt discomfort during VVIR mode. There was no significant statistical difference in cardiopulmonary parameters. DDD and VVIR modes yielded the following respective data: maximum heart rate = 105.7 +/- 21.8 beats/minute versus 107.6 +/- 21.6 beats/minute (NS); maximum workload = 60 +/- 33.4 W versus 59.3 +/- 37.8 W (NS); treadmill duration = 10.1 +/- 3.8 minute versus 10.1 +/- 3.6 minute (NS); oxygen consumption at anaerobic threshold = 14.6 +/- 4.1 mL/kg per minute versus 14.9 +/- 4.6 mL/kg per minute (NS); maximum minute ventilation = 49.6 +/- 9L/min versus 46 +/- 12 L/min (NS); and respiratory quotient = 1.08 +/- 0.15 versus 1.08 +/- 0.13 (NS). We conclude that, during a 1-month follow-up period, no difference was found between DDD and dual sensor VVIR (QT and activity) pacing modes in CAVB patients with regard to quality-of-life and cardiopulmonary performance, though a trend toward an increased sense of well being was noted with the DDD mode.