Late Collateralization of Coronary Arteries From a Previously Non-Functioning Internal Mammary Artery Implant: A Case Summary

A case of severe atheromatous coronary artery disease underwent bilateral internal mammary artery (I.M.A.) implantation for relief of angina pectoris. Thirteen months later one I.M.A. had anastomosed with the native coronary circulation while the other, while patent, provided no collateral flow. Because of recurrent angina, recatheterization at 13 years post-I.M.A. revealed both I.M.A. collateralizing the native coronary arteries in which significant progres sion of atherosclerosis had occurred. The mechanism of this late collateraliza tion is most likely due to progression of coronary artery occlusion.