Is coronary revascularization necessary for patients with well-developed coronary collaterals and coronary artery disease?

Abstract

Coronary collaterals, or “natural bypasses,” are anastomotic connections without an intervening capillary bed between portions of the same coronary artery and between different coronary arteries [1]. They can be visualized on coronary angiography and they potentially offer an important alternative source of blood supply when the original vessel fails to provide sufficient blood [2]. Coronary collaterals may limit infarct size, preserve viability, and prevent ventricular aneurysm formation during an episode of acute coronary occlusion. In patients with stable coronary artery disease, a decrease in ischemic events and a better prognosis have been reported when collaterals are present [3]. However, the relation between well-developed coronary collaterals and prognosis had not been researched exactly. Antoniucci et al. [4] published a study on the significance of preintervention angiographic evidence of coronary collateral circulation in patients with acute MI who underwent primary angioplasty or stenting within 6 h of symptom onset. At 6 months, the mortality rate was lower in patients with coronary collateral circulation compared with patients without collaterals, without clear effects on clinical outcomes. Hendrick et al. [5] researched the relation between collaterals and cardiac death or myocardial infarction at 1 year after coronary revascularization (stent implantation and bypass grafting). They found that the presence of collaterals protected against cardiac death and myocardial infarction in patients with a low risk profile. These studies have compared mortality between the patients who were