Effect of pacing mode on health-related quality of life in the Canadian Trial of Physiologic Pacing

Background Both "physiologic" (dual-chamber or atrial only) or ventricular-pacing-only permanent pacemakers provide chronotropic competence, with unknown health-related quality of life (QOL) differences between these options. The QOL studies within the Canadian Trial of Physiologic Pacing were performed to assess whether QOL differences exist in patients randomized to these 2 pacing modes. Methods Two QOL protocols were performed: 1) a substudy of 269 patients with detailed QOL measures (The Medical Outcomes Study, Short-Form (SF-36), the Pacemaker Syndrome Scale, an activity. scale, and a pacemaker-specific scale) at baseline and 6 months after implantation; and 2) a parent study assessment of QOL in 1721 patients with a 12-item QOL instrument package (SF-6, "ladder of life," and pacemaker syndrome scale) given 6 months after implantation only. Results In the substudy, pacing was associated with an average significant (P < .05) 0.36 SD unit improvement in QOL across all domains (SF-36: 38 +/- 9 to 41 +/- 11 for physical scores, 47 +/- 11 to 52 +/- 9 for mental health scores, both P < .001). Similar improvements were seen with the pacemaker-specific scales. There were no significant differences in the absolute or relative improvement in QOL between assigned pacing modes. The parent study similarly showed no differences in QOL between pacing modalities. Presyncope occurred in 31% of-patients in the physiological pacing group, compared with 38% of the patients in the ventricular, pacing group (P < .01). No other symptoms were different between the 2 groups. Pacemaker dependency, defined,as an escape heart rate <50 beats per minute, did not influence the lack of difference in QOL scores between the 2 assigned pacing modes. Conclusion In this largest randomized assessment of QOL in patients with pacemakers, with the instruments used, there was no significant health-related QOL difference seen between "physiologic" pacing and ventricular pacing.