The Evolution of HRV Parameters During Cardiac Rehabilitation

Hélène De Cannière1, John Morales2, Melanie Schoutteten1, Christophe Smeets3, Willemijn Groenendaal4, Carolina Varon2, Chris Van Hoof4, Sabine Van Huffel2, Pieter Vandervoort5
1Mobile Health Unit, Hasselt University, 2ESAT, 3Future Health Department, Ziekenhuis Oost-Limburg, 4Imec, 5Ziekenhuis Oost-Limburg


Aim To optimize exercise management in cardiac patients following a cardiac rehabilitation program, it is important to study short-term changes of parameters, representative for exercise capacity, at different time points during the exercise program. We hypothesize that studying progression of these parameters in detail could provide more insight into the actual improvement. Therefore, in this study the progression of HRV parameters during short-term intervals throughout rehabilitation was investigated.

Materials and methods Electrocardiographic signals, recorded with a wearable, non-invasive and multiparametric device in 129 cardiac patients following a cardiac rehabilitation program, were analyzed (Age: 63 ± 1, Ejection Fraction: 47% [35-55], Angiotensin converting enzyme (ACE)-inhibitor: 78%). Patients were equipped with the wearable device, every three weeks for five times in total to enable short term follow up. For each patient a segment of five minutes of rest was selected. The R-peaks were detected and the Integral Pulse Frequency Modulation model was used to estimate heart rate variability (HRV). High frequency (HF(n)) and low frequency (LF(n)) powers were normalized. Changes in HF(n) and LF(n) power, RMSDD and SDSD throughout rehabilitation between patients treated with and without ACE-inhibitors were investigated.

Results LFn significantly increased from baseline to end-of study for all patients (p<0.05). For every measurement throughout rehabilitation, LFn tended to be higher in patients treated with ACE-inhibitors. RMSSD and SDSD values were significantly higher (p<0.05) in patients treated with ACE-inhibitors during the initial two measurements. An increasing trend is seen in RMSSD for patients treated without ACE-inhibitors. RMSSD remains constant throughout rehabilitation in the patients treated with ACE-inhibitors.

Conclusion ACE-inhibition, expected to positively affect HRV by preventing the inhibition of the central vagal tone, was characterized by a higher RMSSD at the start of the exercise program, but attenuated the progression of HRV throughout the rehabilitation program.