The incremental benefit of rate-adaptive pacing on exercise performance during cardiac resynchronization therapy.
OBJECTIVE
The purpose of this research was to investigate the effect of using rate-adaptive pacing and atrioventricular interval (AVI) adaptation on exercise performance during cardiac resynchronization therapy (CRT).


BACKGROUND
The potential incremental benefits of using rate-adaptive pacing and AVI adaptation with CRT during exercise have not been studied.


METHODS
We studied 20 patients with heart failure, chronotropic incompetence (<85% age-predicted heart rate [AP-HR] and <80% HR reserve), and implanted with CRT. All patients underwent a cardiopulmonary exercise treadmill test using DDD mode with fixed AVI (DDD-OFF), DDD mode with adaptive AVI on (DDD-ON), and DDDR mode with adaptive AVI on (DDDR-ON) to measure metabolic equivalents (METs) and peak oxygen consumption (VO2max).


RESULTS
During DDD-OFF mode, not all patients reached 85% AP-HR during exercise, and 55% of patients had <70% AP-HR. Compared to patients with >70% AP-HR, patients with <70% AP-HR had significantly lower baseline HR (66 +/- 3 beats/min vs. 80 +/- 5 beats/min, p = 0.015) and percentage HR reserve (27 +/- 5% vs. 48 +/- 6%, p = 0.006). In patients with <70% AP-HR, DDDR-ON mode increased peak exercise HR, exercise time, METs, and VO2max compared with DDD-OFF and DDD-ON modes (p < 0.05), without a significant difference between DDD-OFF and DDD-ON modes. In contrast, there were no significant differences in peak exercise HR, exercise time, METs, and VO2max among the three pacing modes in patients with >70% AP-HR. The percentage HR changes during exercise positively correlated with exercise time (r = 0.67, p < 0.001), METs (r = 0.56, p < 0.001), and VO2max (r = 0.55, p < 0.001).


CONCLUSIONS
In heart failure patients with severe chronotropic incompetence as defined by failure to achieve >70% AP-HR, appropriate use of rate-adaptive pacing with CRT provides incremental benefit on exercise capacity during exercise.
Tse
Hung-Fat
HF
Cardiology Division, Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong, China.
Siu
Chung-Wah
CW
Lee
Kathy L F
KL
Fan
Katherine
K
Chan
Hon-Wah
HW
Tang
Man-Oi
MO
Tsang
Vella
V
Lee
Stephen W L
SW
Lau
Chu-Pak
CP
D000222:Adaptation, Physiological; D000368:Aged; D000465:Algorithms; D001283:Atrioventricular Node / Q000503:physiopathology; D002303:Cardiac Output, Low / Q000503:physiopathology* / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D015444:Exercise; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index