Exercise-based cardiac rehabilitation for patients with atrial fibrillation

Background

Atrial fibrillation (AF) is the most common irregular heart beat a person can experience. It affects the heart by 'taking over' and sending out electric pulses that makes the heartbeat irregular and inefficient. Symptoms can include irregular heartbeat, shortness of breath, weakness, dizziness, and fainting. Exercise-based cardiac rehabilitation aims to restore health in people with atrial fibrillation or those who have been treated for atrial fibrillation, through regular exercise.

Review question

This systematic review assessed the benefits and harms of exercise-based cardiac rehabilitation in adults with atrial fibrillation.

Study characteristics

We included six randomised trials with a total of 421 participants. The evidence is current to July 2016.

Key results

There were two deaths and eight serious adverse events (harmful side effects) reported in the six trials, therefore, we had insufficient data to conclude whether exercise-based cardiac rehabilitation improved outcomes that matter the most to patients, such as death and serious adverse events (e.g. hospitalisation). Exercise-based rehabilitation was not found to have a clinically relevant impact on quality of life for the patient group, but may increase exercise capacity.

Quality of the evidence

The quality of the evidence ranged from moderate to very low for all outcomes. It was possible for people in the trials to know to which intervention group they were randomised, the reporting of the results was not complete in many trials, and for some outcomes, the results varied across trials. These considerations limit our confidence in the overall results of the review.

Conclusions

Further randomised clinical trials that are conducted with low risks of bias and low risks of the play of chance, in a broader population of patients with AF, are needed to assess the impact of exercise-based interventions.

Authors' conclusions: 

Due to few randomised patients and outcomes, we could not evaluate the real impact of exercise-based cardiac rehabilitation on mortality or serious adverse events. The evidence showed no clinically relevant effect on health-related quality of life. Pooled data showed a positive effect on the surrogate outcome of physical exercise capacity, but due to the low number of patients and the moderate to very low-quality of the underpinning evidence, we could not be certain of the magnitude of the effect. Future high-quality randomised trials are needed to assess the benefits and harms of exercise-based cardiac rehabilitation for adults with atrial fibrillation on patient-relevant outcomes.

Read the full abstract...
Background: 

Exercise-based cardiac rehabilitation may benefit adults with atrial fibrillation or those who had been treated for atrial fibrillation. Atrial fibrillation is caused by multiple micro re-entry circuits within the atrial tissue, which result in chaotic rapid activity in the atria.

Objectives: 

To assess the benefits and harms of exercise-based rehabilitation programmes, alone or with another intervention, compared with no-exercise training controls in adults who currently have AF, or have been treated for AF.

Search strategy: 

We searched the following electronic databases; CENTRAL and the Database of Abstracts of Reviews of Effectiveness (DARE) in the Cochrane Library, MEDLINE Ovid, Embase Ovid, PsycINFO Ovid, Web of Science Core Collection Thomson Reuters, CINAHL EBSCO, LILACS Bireme, and three clinical trial registers on 14 July 2016. We also checked the bibliographies of relevant systematic reviews identified by the searches. We imposed no language restrictions.

Selection criteria: 

We included randomised controlled trials (RCT) that investigated exercise-based interventions compared with any type of no-exercise control. We included trials that included adults aged 18 years or older with atrial fibrillation, or post-treatment for atrial fibrillation.

Data collection and analysis: 

Two authors independently extracted data. We assessed the risk of bias using the domains outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We assessed clinical and statistical heterogeneity by visual inspection of the forest plots, and by using standard Chi² and I² statistics. We performed meta-analyses using fixed-effect and random-effects models; we used standardised mean differences where different scales were used for the same outcome. We assessed the risk of random errors with trial sequential analysis (TSA) and used the GRADE methodology to rate the quality of evidence, reporting it in the 'Summary of findings' table.

Main results: 

We included six RCTs with a total of 421 patients with various types of atrial fibrillation. All trials were conducted between 2006 and 2016, and had short follow-up (eight weeks to six months). Risks of bias ranged from high risk to low risk.The exercise-based programmes in four trials consisted of both aerobic exercise and resistance training, in one trial consisted of Qi-gong (slow and graceful movements), and in another trial, consisted of inspiratory muscle training.

For mortality, very low-quality evidence from six trials suggested no clear difference in deaths between the exercise and no-exercise groups (relative risk (RR) 1.00, 95% confidence interval (CI) 0.06 to 15.78; participants = 421; I² = 0%; deaths = 2). Very low-quality evidence from five trials suggested no clear difference between groups for serious adverse events (RR 1.01, 95% CI 0.98 to 1.05; participants = 381; I² = 0%; events = 8). Low-quality evidence from two trials suggested no clear difference in health-related quality of life for the Short Form-36 (SF-36) physical component summary measure (mean difference (MD) 1.96, 95% CI -2.50 to 6.42; participants = 224; I² = 69%), or the SF-36 mental component summary measure (MD 1.99, 95% CI -0.48 to 4.46; participants = 224; I² = 0%). Exercise capacity was assessed by cumulated work, or maximal power (Watt), obtained by cycle ergometer, or by six minute walking test, or ergospirometry testing measuring VO2 peak. We found moderate-quality evidence from two studies that exercise-based rehabilitation increased exercise capacity, measured by VO2 peak, more than no exercise (MD 3.76, 95% CI 1.37 to 6.15; participants = 208; I² = 0%); and very low-quality evidence from four studies that exercise-based rehabilitation increased exercise capacity more than no exercise, measured by the six-minute walking test (MD 75.76, 95% CI 14.00 to 137.53; participants = 272; I² = 85%). When we combined the different assessment tools for exercise capacity, we found very low-quality evidence from six trials that exercise-based rehabilitation increased exercise capacity more than no exercise (standardised mean difference (SMD) 0.86, 95% CI 0.46 to 1.26; participants = 359; I² = 65%). Overall, the quality of the evidence for the outcomes ranged from moderate to very-low.

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