Introduction
Atrial fibrillation (AF) is the most common cardiac arrhythmia and associated with increased risks of stroke, heart failure, dementia and death.1 AF has a prevalence of approximately 2% in adults and increasing incidence, mainly due to the ageing population.2 3 AF is a highly heterogeneous condition split in to five diagnostic categories: first-diagnosed AF (patient presents with AF for the first time), paroxysmal AF (self-limiting and usually the rhythm converts spontaneously to sinus (normal) rhythm within 48 hours), persistent AF (AF episode lasts longer than 7 days, or requires cardioversion), long-standing persistent AF (duration of AF exceeds 1 year) and permanent AF (accepted by the patient (and physician) and no rhythm control interventions are used).4 Patients with AF can experience palpitations, shortness of breath, fatigue, dizziness and syncope (fainting), depression, anxiety and reduced exercise capacity.3–6
Current AF management mainly focuses on rate and rhythm control and reducing stroke risk and its associated morbidity and mortality.4 However, although effective in managing symptoms and stroke risk, current treatments do not focus on patients’ exercise capacity, ability to self-manage and mental health.7–9 Poor health-related quality of life (HRQoL) therefore remains a common and important problem of patients with AF receiving conventional medical therapy. HRQoL in patients with AF has been shown to be lower than age and sex-matched members of the general population and other cardiac groups, including coronary heart disease (CHD).9 Beyond medical management, evidence suggests AF may be controlled by improving lifestyle.10 11 One aspect of lifestyle therapy that is poorly understood, with respect to AF, is regular exercise.12
Mechanisms by which exercise may improve health outcomes for patients with AF include atrial remodelling, antiarrhythmic effects via changes in autonomic control, reduced blood pressure, reduced bodyweight and reduced lipids.13 For example, a study evaluated the long-term impact of weight loss on rhythm control of 355 obese patients (body mass index (BMI) ≥27 kg/m2) with AF. Long-term sustained weight loss (≥10%) was associated with significant reduction of AF burden and maintenance of sinus rhythm.14 Exercise has also been shown to stimulate improvements in mental health through improvements in self-efficacy and reduced inflammation.15 16
A substantive body of evidence supports the benefits of exercise-based cardiac rehabilitation (CR) for CHD (post-myocardial and post-revascularisation)17 18 and heart failure populations.12 A recent meta-analysis of 33 randomised trials found that exercise-based CR reduced the risk of overall and heart failure-specific hospitalisation and resulted in improvements in HRQoL compared with usual medical care.19 AF is a common comorbidity in patients with CHD and heart failure referred to exercise-based CR. However, given the sparse evidence for CR specifically targeted for patients with AF, the 2012 European Society of Cardiology and 2011 American College of Cardiology/American Heart Association guidelines for the management of AF do not formally recommend rehabilitation.4 20 21
Since these guidelines were published, a Cochrane review in 2017 has found that exercise-based rehabilitation programmes targeted at AF patients significantly increased their exercise capacity (standardised mean difference (SMD): 0.86, 95% CI 0.46 to 1.26) compared with no exercise control. However, only a small volume of evidence (six randomised trials in 421 patients with AF) of moderate to very low-quality and of short-term follow-up (up to 6 months) was identified and little or no data were available on the impact on HRQoL or clinical events, such as mortality and hospitalisation.
Aware that a number of trials have been published since this 2017 Cochrane review, we sought to undertake a de novo systematic review and meta-analysis to provide a contemporary summary of the impact of exercise-based CR specifically aimed at patients with AF.
The specific aims of this review were to: (i)⇓ investigate if exercise-based CR reduces the risk of mortality and hospitalisation of patients with AF; (ii) to identify if markers of cardiac function and AF risk are altered with exercise-based CR; (iii) and to confirm whether exercise-based CR increases exercise capacity and HRQoL in patients with AF.