The Influence of Comprehensive Cardiac Rehabilitation on Heart Rate Variability Indices after CABG is More Effective than after PCI

Exercise training and cardiac autonomic function following coronary artery bypass grafting: a systematic review and meta-analysis

BACKGROUND

Exercise training improves cardiac autonomic function is still debatable in patients with coronary artery bypass grafting (CABG). The aim of the present review is to assess the effect of exercise on CABG patient's heart rate variability (HRV) and heart rate recovery (HRR) parameters.

MAIN BODY

Databases (PubMed, Web of Science and PEDro) were accessed for systematic search from inception till May 2022. Eleven potential studies were qualitatively analyzed by using PEDro and eight studies were included in the quantitative synthesis. Meta-analysis was conducted by using a random-effect model, inverse-variance approach through which standardized mean differences (SMDs) were estimated. The analysis of pooled data showed that exercise training improved HRV indices of standard deviation of the R-R intervals (SDNN) [SMD 0.44, 95% CI 0.17, 0.71, p = 0.002], square root of the mean squared differences between adjacent R-R intervals (RMSSD) [SMD 0.68, 95% CI 0.28, 1.08, p = 0.0008], high frequency (HF) [SMD 0.58, 95% CI 0.18, 0.98, p = 0.005] and low frequency-to-high frequency (LF/HF) ratio [SMD - 0.34, 95% CI - 0.65, - 0.02, p = 0.03].

CONCLUSIONS

Exercise training enhances cardiac autonomic function in CABG patients. Owing to the methodological inconsistencies in assessing HRV, the precise effect on autonomic function still remains conflicted. Future high-quality trials are needed focusing on precise methodological approach and incorporation of various types of exercise training interventions will give clarity regarding autonomic adaptations post-exercise training in CABG. Trial registration CRD42021230270 , February 19, 2021.

Effects of early rehabilitation on functional outcomes in patients after coronary artery bypass graft surgery: a randomized controlled trial

Objective

This study evaluated the effectiveness, feasibility, and safety of early rehabilitation for patients after coronary artery bypass graft (CABG) surgery.

Methods

In a three-arm randomized controlled trial, patients who underwent CABG from January 2018 to June 2018 were randomly assigned to one of three groups: (i) usual care (UC group); (ii) UC + single general ward rehabilitation (SGR group); and (iii) UC + general ward rehabilitation and intensive care unit (ICU) rehabilitation (IGR group). The primary outcome was the Barthel Index scores.

Results

The Barthel Index score for UC (75.3 ± 12.1) was significantly lower than that of both SGR (86.2 ± 14.1) and IGR (89.1 ± 15.5). There was no significant difference in the Barthel Index scores between the SGR and IGR groups. Statistically significant differences were found in the length of ICU stay and post-operative hospital stay but not in post-operative pulmonary complications (PPC) or atrial fibrillation between the three groups.

Conclusion

Early rehabilitation implemented during ICU stay and on the general ward resulted in significant improvements in functional independence and could be a safe part of routine care post-CABG.

Effect of Early Rehabilitation on Physical Function in Patients Undergoing Coronary Artery Bypass Grafting: A Nationwide Inpatient Database Study

It is unclear when to begin rehabilitation after coronary artery bypass grafting (CABG) in the intensive care unit (ICU). Using the Japanese Diagnosis Procedure Combination inpatient database from 2010 to 2018, we identified adult patients who underwent a CABG and who were admitted to the ICU for ≥3 consecutive days from the date of their CABG. Patients who started any rehabilitation program prescribed by physicians or therapists within 3 days of CABG were defined as the early rehabilitation group, and the remaining patients were defined as the usual care group. We identified 30,568 eligible patients, with 13,150 (43%) patients in the early rehabilitation group. An inverse probability of treatment weighting analyses showed that the Barthel Index score at discharge in the early rehabilitation group was significantly higher than that in the usual care group (difference: 3.2; 95% confidence interval: 1.5–4.8). The early rehabilitation group had significantly lower in-hospital mortality, total hospitalization costs, length of ICU stay, and hospital stay vs. the usual care group. Our results suggested that early rehabilitation by physicians or therapists beginning within 3 days of CABG was safe, as suggested by the low mortality and improved physical function in patients who underwent CABG.

Exercise-based cardiac rehabilitation and parasympathetic function in patients with coronary artery disease: a systematic review and meta-analysis

PURPOSE

The effects of exercise-based cardiac rehabilitation (CR) on parasympathetic modulation are controversial. This systematic review and meta-analysis aims to (a) determine the effect of exercise-based CR on heart-rate-derived indices associated with cardiac parasympathetic modulation in resting and post-exercise conditions in coronary artery disease (CAD) patients and (b) identify the possible moderator variables of the effect of exercise-based CR on parasympathetic modulation.

METHODS

We searched CENTRAL and Web of Science up to November 2018 for the following terms: adult CAD patients, controlled exercise-based CR interventions and parasympathetic modulation measured in resting (vagal-related heart rate variability [HRV] indices of the root mean square of the differences in successive in RR interval [RMSSD] and high frequency [HF]) and post-exercise (heart rate recovery [HRR]) pre- and post-intervention. We estimated a random-effects model of standardised mean difference (SMD) and mean difference (MD) for vagal-related HRV indices and HRR, respectively. We assessed the influence of categorical and continuous variables.

RESULTS

The overall effect size showed significant differences in RMSSD (SMD₊ = 0.30; 95% confidence interval [CI] = 0.12-0.49) and HRR (MD₊ = 5.35; 95% CI = 4.08-6.61 bpm) in favour of the exercise-based CR group. The overall effect size showed no differences in HF between groups (SMD₊ = 0.14; 95% CI,  -0.12-0.40). Heterogeneity analyses reached statistical significance, with high heterogeneity for HF (p < 0.001; I² = 70%) and HRR (p < 0.001; I² = 85%). Analysis of the moderator variables showed that the effect on HRR is greater in young patients (p = 0.008) and patients treated with percutaneous intervention (p = 0.020).

CONCLUSIONS

Exercise-based CR improves the post-exercise parasympathetic function, with greater effects in younger CAD patients and in those who were revascularised with percutaneous intervention. The effects on resting parasympathetic function are more controversial due to methodological inconsistencies in measuring HRV, with the use of RMSSD recommended instead of HF because its results show higher consistency. Future studies involving women, focusing on methodological issues, and performing other training methods are needed to increase our knowledge about this topic.