Intrinsic Heart Rate Response as a Predictor of Rate-Adaptive Pacing Benefit

¹ From the 1. Medizinische Klinik, Klinikum rechts der Isar, Technische Universität Miünchen, München, Germany

Objective: More than half of the pacemaker systems now being implanted can be rate adaptively paced. Our objective was to determine which patients benefit from rate-adaptive pacing in terms of improvement in maximum performance and aerobic capacity.

Methods: Thirty patients with implanted accelerometer-driven, rate-adaptive pacemakers underwent a standardized, ergospirometrically and maximally symptoms=limited cardiopulmonary exercise (CPX) stress test with both rate-adaptive and fixed-rate stimulation in a randomized order. The patients were divided into three groups depending on the intrinsic heart rate achieved during maximum workload: group 1 achieved 90 beats per minute (bpm), group 2 achieved 90 to 110 bpm, and group 3 achieved >110 bpm.

Results: Group 1 demonstrated a significant increase (p0.01) in maximum oxygen uptake from 16.4±5.6 mL/kg/min with fixed-rate pacing to 23.2±11.1 mL/kg/min (+41.5%) with rate-adaptive pacing. At the anaerobic threshold, oxygen uptake significantly increased (p0.01) from 11.8±2.7 mL/kg/min to 15.7±5 mL/kg/min (+33.1%). Group 2 patients showed an increase in maximum oxygen uptake from 23.3±5.4 mL/kg/min to 25.3±4.9 mL/kg/min (+8.5%., p0.05) as well as an increase in oxygen uptake at the anaerobic threshold from 15.9±2.6 mL/kg/min to 18.1±2.9 mL/kg/min (+13.8%, p <0.05) with rate-adaptive pacing. Group 3 demonstrated no significant difference between the two pacing methods (from 25.6±9.4 mL/kg/min to 25.9±9.3 mL/kg/min and from 15.8±5.5 mL/kg/min to 16.3±6 mL/kg/min). No difference in maximum oxygen uptake and in oxygen uptake at the anaerobic threshold was evident among the three groups when paced rate adaptively (not significant).

Conclusion: The second-generation, accelerometer controlled rate-adaptive pacemakers used in testing enabled a stress-oriented heart rate increase and an age- and gender-dependent adequate matching of maximum performance. The benefit from a rate-adaptive system to the patient increases as his or her chronotropic reserve limitation became more pronounced.

Key Words: accelerometer • aerobic capacity • intrinsic heart rate • rate-adaptive cardiac pacing

Submitted on May 6, 1994
Accepted on August 2, 2007

This article has been cited by other articles:

				M. Kindermann, B. Schwaab, N. Finkler, S. Schaller, M. Bohm, and G. Frohlig Defining the optimum upper heart rate limit during exercise. A study in pacemaker patients with heart failure Eur. Heart J., August 2, 2002; 23(16): 1301 - 1308. [Abstract] [PDF]

				J. Lass, J. Kaik, K. Meigas, H. Hinrikus, and A. Blinowska Evaluation of the quality of rate adaptation algorithms for cardiac pacing Europace, January 1, 2001; 3(3): 221 - 228. [Abstract] [PDF]