The effect of atrial-based pacing on exercise capacity as measured by the 6-minute walk test: A substudy of the Canadian Trial of Physiological Pacing (CTOPP)

Baranchuk, Adrian; Healey, Jeff S.; Thorpe, Kevin E.; Morillo, Carlos A.; Nair, Girish; Crystal, Eugene; Kerr, Charles R.; Connolly, Stuart J.; CTOPP Investigators,

doi:10.1016/j.hrthm.2007.03.042

« Previous Next »Heart Rhythm
Volume 4, Issue 8 , Pages 1024-1028, August 2007

The effect of atrial-based pacing on exercise capacity as measured by the 6-minute walk test: A substudy of the Canadian Trial of Physiological Pacing (CTOPP)

Adrian Baranchuk, MD
- Queen’s University, Kingston, Ontario, Canada
Jeff S. Healey, MD
- The Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
- Dr. Healey is supported by a fellowship grant from the Heart and Stroke Foundation of Canada and Astra-Zeneca Canada Ltd.
- Address reprint requests and correspondence: Jeff S. Healey, McMaster University, 237 Barton Street East, Hamilton, Ontario, Canada, L8L 2X2.
Kevin E. Thorpe, MMath
- University of Toronto, Toronto, Ontario, Canada
Carlos A. Morillo, MD, FACC
- The Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
Girish Nair, MD
- The Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
Eugene Crystal, MD
- University of Toronto, Toronto, Ontario, Canada
Charles R. Kerr, MD, FACC
- University of British Columbia, Vancouver, British Columbia, Canada.
Stuart J. Connolly, MD, FACC
- The Population Health Research Institute, McMaster University, Hamilton, Ontario, Canada
CTOPP Investigators

Received 26 February 2006; accepted 31 March 2007. published online 13 April 2007.

Background

Although several randomized trials have detected no reduction in major cardiovascular events with the routine use of dual-chamber as opposed to ventricular pacemakers, many individuals continue to advocate their use as a means of improving exercise capacity.

Methods

The Canadian Trial of Physiological Pacing (CTOPP) trial is the largest trial comparing ventricular pacing to atrial-based pacing (atrial or dual-chamber) in patients with bradycardia. All patients in this trial were asked to complete a 6-minute hall walk test (6MWT) at the time of their first study follow-up. The distance walked in 6 minutes and the patient’s heart rate before and immediately after the walk were recorded.

Results

Of the 2568 patients in the CTOPP, 76% completed the 6MWT. The mean distance walked was 350 ± 127 m in the ventricular pacing group and 356 ± 127 m in the atrial-based group (P = NS). Similarly, there was no difference in the change in heart rate between the two groups (17 ± 13 vs. 18 ± 12 bpm: P = NS). However, among patients with an unpaced heart rate of ≤60 bpm, patients assigned to atrial-based pacing walked farther than those randomized to ventricular pacing (361 ± 127 vs. 343 ± 121 m; P = .04). This was not associated with a difference in heart rate. The use of rate-adaptive pacing, irrespective of the pacing mode, resulted in a greater increase in heart rate with the 6MWT but no increase in the total distance walked.

Conclusion

The routine use of atrial-based pacemakers, instead of ventricular pacemakers, does not improve exercise capacity, as measured by the 6MWT. However, patients with an unpaced heart rate of ≤60 bpm may achieve a modest increase in their exercise capacity with atrial-based pacing.

Keywords: Pacemaker, Pacing mode, Exercise capacity, Quality of life