Effects of Pharmacologic, Non-Pharmacologic, and Exercise-Based Interventions on Coronary Collateral Circulation: A Scoping Review.

INTRODUCTION

Coronary collaterals are vascular connections that bridge epicardial arteries and supply blood to the oxygen-deprived myocardium in patients with coronary artery disease (CAD). This comprehensive review aimed to identify and evaluate potential interventions that may enhance the growth of coronary collateral vessels.

METHODS

We conducted a scoping review of five databases to identify relevant studies that focused on interventions that may promote coronary collateral circulation in patients with CAD.

RESULTS

Our search identified 23 studies that met our inclusion criteria. Studies (n = 7) using pharmacologic agents (i.e., angiotensin-converting enzyme inhibitors, granulocyte macrophage colony stimulating factor, statins, human recombinant basic fibroblast growth factor, and granulocyte macrophage colony stimulating factor) were found to improve collateralization, as did the non-pharmacologic studies (n = 13) (i.e., exercise training, electrical stimulation, and enhanced external counterpulsation), which formed most of the studies. Three studies found benefits of a combination of exercise and heparin. Improvements were seen in collateralization as measured by the coronary flow index and Rentrop scores across all interventions. Effect sizes from randomized trials with pharmacologic, non-pharmacologic, and exercise-based interventions ranged between 0.4 and 0.7.

CONCLUSION

This review provides a comprehensive overview and update of the existing literature on interventions that may promote coronary collateralization (CC). In summary, we observed a few pharmacological and non-pharmacological (exercise, electrical stimulation, and enhanced external counterpulsation) interventions that have shown a positive effect on CC. These data provide a framework for more robust trials regarding the proliferation and clinical significance of enhanced CC in cardiovascular outcomes in patients with known or occult CAD.