ACCELEROMETER-BASED ADAPTIVE-RATE PACING - A MULTICENTER STUDY

A new adaptive rate pacemaker, using an accelerometer to detect body motion as an indicator of metabolic demand, was evaluated in 13 centers located in five countries. During the study, 55 patients with a broad range of indications were implanted with the EXCEL(TM) VR single chamber pacemaker. One month evaluations were completed on a subgroup of 37 patients. The pacemaker response was optimized before discharge using a simple walking test. An ''exercise test'' recording feature in the programmer eliminated the need for ECG monitoring. At nominal settings, the mean (+/- SD) pacing rate increased 29 +/- 9 ppm while walking slowly and 44 +/- 11 ppm (n = 33) during a brisk walk. This information was used to optimize the parameter settings. Without further changes to the programmed settings the patients were subsequently tested 2-4 weeks postimplant with a symptom-limited treadmill test using the chronotropic assessment exercise protocol (CAEP). Mean pacing rate increased from 74.5 +/- 2.5 ppm (n = 24) at rest to 118.6 +/- 12.2 ppm (n = 21) at 3 mph/6% grade to 143.5 +/- 2.5 ppm (n = 2) at 3.8 mph/8% grade. Conclusion. The individual responses were proportional to the physical exertion imposed on the patients. Pacing rates were considered to be appropriate using the chronotropic response zone as a criterion for appropriate rate modulation. A simple walking test utilizing the exercise test facility, results in appropriate optimization of the pulse generator to the individual patient.