Rate responsive pacemakers: a rapid assessment protocol.
BACKGROUND
Rate responsive (RR) pacemakers are commonly implanted with nominal conservative factory-set responsiveness, which is usually accepted because established exercise protocols are time-consuming. We aimed for efficient assessment of RR pacemaker settings.


METHODS
We tested exercise heart rates in controls and paced patients using a brief exercise test that approximates real-life levels of exertion. The test used a nonmotorized treadmill: 30 seconds walking at patient-determined speed followed by 15 seconds brisk exertion. Subjects totaled 110: 26 with RR pacemakers; 22 with non-RR pacers; 27 "sick" nonpaced control patients; and 35 healthy controls. Heart rate (HR) was measured prior to exercise, after 30 seconds of casual walk, after 15 seconds of brisk walk, and 1 minute into recovery. Testing required <5 minutes from set-up to recovery.


RESULTS
The 26 RR pacer patients had a mean HR at rest = 74 +/- 10 beats per minute (bpm), walk = 87 +/- 14, and brisk = 94 +/- 18 (increase 27%). Non-RR pacer patients (n = 22): rest = 73 +/- 12 bpm, walk = 88 +/- 14, and brisk = 94 +/- 17 (increase 24.3%, P = 0.60 vs RR patients). "Sick" controls (n = 27): rest = 78 +/- 14 bpm, walk = 102 +/- 17, and brisk = 117 +/- 18 (increase 51.9%, P< 0.001 vs RR pts). For the healthy controls, HRs were at rest 83+/11 bpm, walk = 104 +/- 12, and brisk = 117 +/- 13 (P< 0.001 compared to both paced groups; P = NS vs sick controls).


CONCLUSIONS
Nominal RR settings may be suboptimal for many patients. The nonmotorized treadmill test allows quick and inexpensive assessment of RR programming, with the potential for efficient RR optimization.
Shaber
Justin D
JD
Department of Medicine, Cardiology Division, Arrhythmia Service, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York 10467, USA.
Fisher
John D
JD
Ramachandra
Indiresha
I
Gonzalez
Christian
C
Rosenberg
Lauren
L
Ferrick
Kevin J
KJ
Gross
Jay N
JN
Kim
Soo G
SG
D000704:Analysis of Variance; D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000628:therapy*; D002304:Cardiac Pacing, Artificial / Q000379:methods*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial