BACKGROUND-Despite its proven benefits and need, women are significantly less likely to participate in and complete cardiac rehabilitation (CR) than men. The purpose of this study was to quantitatively investigate sex differences in CR barriers by participation status.

Background-Cardiac rehabilitation (CR) is an established means of reducing mortality, yet is grossly under-utilized. This is due to both health system and patient-level factors, issues which have yet to be investigated concurrently. This study utilized a hierarchical design to examine physician and patient-level factors affecting verified CR enrollment.

| Despite recommendations in clinical practice guidelines, evidence suggests that utilization of cardiac rehabilitation (CR) following indicated cardiac events is low. Referral strategies, such as automatic referral, have been advocated to improve CR utilization. In this Review, we evaluate the effects of referral strategies on rates of CR referral and enrollment. Referral strategies are categorized as 'automatic' (the use of electronic health records or systematic discharge order sets), as 'liaison' (discussions with allied healthcare providers), or as 'other' (for example, the use of motivational letter to patients). The highest rates of CR referral have been achieved in studies implementing automatic referral orders, whereas the highest rates of CR enrollment have resulted from a combination of automatic and liaison methods. Overall, innovative referral strategies significantly increase CR utilization. While further investigation is needed, institutions should evaluate their CR referral practice in light of these findings.