Abstract 2799: Prompt Human Coronary Collateral Vasomotor Function Induced by Dynamic Physical Exercise
INTRODUCTION: The existence of coronary collateral vessels and their benefit against cardiac events have been recognized for years, but their functional capacity in response to physical exercise has remained elusive. Via endothelial shear stress, the fundamental stimulus for collateral development, exercise theoretically leads to collateral vasodilation and recruitment by an increase in heart rate and blood pressure during exercise. Moreover, the phenomenon of “walking through angina” indicates that collateral function and physical activity are related and their interaction is of clinical relevance. The purpose of the present study in humans with stable coronary artery disease was to assess the instantaneous response of coronary collateral function to dynamic physical exercise.
METHODS: A total of fifteen patients undergoing percutaneous coronary intervention (PCI)because of stable angina pectoris were included in the study. Collateral function was determined before and during the last minute of a 6-minute protocol of supine bicycle exercise during radial access coronary angiography. Collateral flow index CFI (no unit) was assessed by means of a pressure guide wire distal to the balloon-occluded artery. To avoid confounding due to recruitment of coronary collaterals by repetitive balloon occlusions, patients were randomly assigned to a group ‘rest first’ with CFI measurement during rest followed by a measurement during cycling, and to a group ‘exercise first’ with antecedent CFI measurement during exercise before measurement at rest.
RESULTS: Collateral flow index was 0.144 (0.112) and 0.249 (0.183) during rest and during exercise, respectively (p=0.002). CFI of the group ‘rest-first’ was 0.114 (0.060) during rest and 0.206 (0.100) during exercise (p=.046). In the group ‘exercise first’, CFI at rest was 0.163 (0.136), during exercise, CFI was 0.278 (0.223) (p=0.015).
CONCLUSION: Dynamic exercise instantaneously improves collateral function by a factor of 1.8 (i.e. coronary collateral flow reserve). The phenomenon of “walking through angina” seems to be partially explainable by this functional capacity to increase flow, present also in collateral arteries.