Abstract: Overall, we included 26 studies with 5299 participants (29 comparisons). Participants were primarily male (64.2%). Ten (38.5%) studies included patients with heart failure. We assessed most studies as having low or unclear risk of bias. Sixteen studies (3164 participants) reported interventions to improve enrolment in cardiac rehabilitation, 11 studies (2319 participants) reported interventions to improve adherence to cardiac rehabilitation, and seven studies (1567 participants) reported interventions to increase programme completion. Researchers tested a variety of interventions to increase utilisation of cardiac rehabilitation. In many studies, this consisted of contacts made by a healthcare provider during or shortly after an acute care hospitalisation. Low-quality evidence shows an effect of interventions on increasing programme enrolment (19 comparisons; risk ratio (RR) 1.27, 95% confidence interval (CI) 1.13 to 1.42). Meta-regression revealed that the intervention deliverer (nurse or allied healthcare provider; P = 0.02) and the delivery format (face-to-face; P = 0.01) were influential in increasing enrolment. Low-quality evidence shows interventions to increase adherence were effective (nine comparisons; standardised mean difference (SMD) 0.38, 95% CI 0.20 to 0.55), particularly when they were delivered remotely, such as in home-based programs (SMD 0.56, 95% CI 0.37 to 0.76). Moderate-quality evidence shows interventions to increase programme completion were also effective (eight comparisons; RR 1.13, 95% CI 1.02 to 1.25), but those applied in multi-centre studies were less effective than those given in single-centre studies, leading to questions regarding generalisability. A moderate level of statistical heterogeneity across intervention studies reflects heterogeneity in intervention approaches. There was no evidence of small-study bias for enrolment (insufficient studies to test for this in the other outcomes). With regard to secondary outcomes, no studies reported on harms associated with the interventions. Only two studies reported costs. In terms of equity, trialists tested interventions designed to improve utilisation among women and older patients. Evidence is insufficient for quantitative assessment of whether women-tailored programmes were associated with increased utilisation, and studies that assess motivating women are needed. For older participants, again while quantitative assessment could not be undertaken, peer navigation may improve enrolment. Interventions may increase cardiac rehabilitation enrolment, adherence and completion; however the quality of evidence was low to moderate due to heterogeneity of the interventions used, among other factors. Effects on enrolment were larger in studies targeting healthcare providers, training nurses, or allied healthcare providers to intervene face-to-face; effects on adherence were larger in studies that tested remote interventions. More research is needed, particularly to discover the best ways to increase programme completion.

Plain-language summary: We searched a wide variety of scientific databases for randomised controlled trials (studies that allocate participants to one of two or more treatment groups in a random manner) in adults (over 18 years of age) who had a heart attack, had angina (chest pain), underwent coronary artery bypass grafting (a surgical procedure that diverts blood around narrowed or clogged sections of the major arteries to improve blood flow and oxygen supply to the heart muscle) or percutaneous coronary intervention (a procedure that opens up blocked coronary arteries), or with heart failure who were eligible for cardiac rehabilitation. Reviewers found 26 trials (5299 participants) that were suitable for inclusion (16 trials of interventions to improve enrolment, eight trials of interventions to improve adherence, and seven trials of interventions to improve programme completion). These studies evaluated a variety of techniques to improve utilisation such as providing peer support, starting cardiac rehabilitation early after hospitalisation, providing patient education, offering cardiac rehabilitation outside a hospital setting, and offering shorter programmes or women-only programmes. Strategies to increase enrolment were effective, particularly those that targeted healthcare providers, training nurses, or allied healthcare providers to intervene face-to-face. Interventions to increase adherence to programmes and to increase completion were effective, but it remains unclear which specific strategies were implemented. We found no studies providing information about potential harms and two studies reporting costs of these strategies to increase use of cardiac rehabilitation. Some studies provided interventions to increase rehabilitation utilisation in women and older patients. Evidence was insufficient for quantitative assessment of whether women-tailored programmes were associated with increased utilisation, but motivating women appears key. For older participants, qualitative analysis suggested that peer support or postdischarge visits may improve enrolment, and group sessions promoting self-regulation skills may increase completion. Most of the included studies were of good quality (i.e. low risk of arriving at wrong conclusions because of favouritism by researchers). The quality of the evidence was low for enrolment and adherence and was moderate for completion. Publication bias for enrolment was not evident.