Myocardial perfusion in patients with total occlusion of a single coronary artery with and without collateral circulation

Background. Previous studies that investigated the effects of coronary collateral circulation on myocardial perfusion were compromised by inclusion of patients with multivessel coronary artery disease, incomplete occlusion, prior myocardial infarction, or a combination of these. In this study we ascertained the relationship between angiographic collateral circulation and myocardial perfusion only in patients with total occlusion of a single coronary artery, in the absence of myocardial infarction or significant stenosis in the other coronary arteries. Methods and Results. Seventy-one consecutive patients underwent stress myocardial single photon emission computed tomography within 90 days of angiography. Collateral circulation was present in 49 patients and absent in 22 patients. All but 2 patients had abnormal perfusion by single photon emission computed tomography imaging, with a mean defect size of 19% +/- 12%, and most (83%) had reversible perfusion defects. Defect count activities improved from stress to rest (or redistribution) (45% +/- 13% to 59% +/- 14%, P < .001). Abnormal myocardial perfusion occurred with similar frequency in patients with collateral circulation and in those without it. Total defect size was 19 % 12% in patients with and 18 % +/- 11% in those without collateral circulation (P = not significant). The extent of reversibility and defect count activity during stress and rest were similar in patients with collateral circulation and in those without it. Conclusions. In patients with a single-vessel total coronary occlusion and without myocardial infarction, stress-induced myocardial ischemia is almost always present, irrespective of presence or absence of angiographic collaterals. These data lend support to the premise that collateral circulation is rather insufficient to prevent stress-induced ischemia, although it can preserve myocardial viability.