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

Background. Previous studies that investigated the effects of coronary coll ateral circulation on myocardial perfusion were compromised by inclusion of patients with multivessel coronary artery disease, incomplete occlusion, p rior myocardial infarction, or a combination of these. In this study we asc ertained the relationship between angiographic collateral circulation and m yocardial perfusion only in patients with total occlusion of a single coron ary artery, in the absence of myocardial infarction or significant stenosis in the other coronary arteries. Methods and Results. Seventy-one consecutive patients underwent stress myoc ardial single photon emission computed tomography within 90 days of angiogr aphy. Collateral circulation was present in 49 patients and absent in 22 pa tients. All but 2 patients had abnormal perfusion by single photon emission computed tomography imaging, with a mean defect size of 19% +/- 12%, and m ost (83%) had reversible perfusion defects. Defect count activities improve d from stress to rest (or redistribution) (45% +/- 13% to 59% +/- 14%, P < .001). Abnormal myocardial perfusion occurred with similar frequency in pat ients with collateral circulation and in those without it. Total defect siz e was 19 % <plus/minus> 12% in patients with and 18 % +/- 11% in those with out collateral circulation (P = not significant). The extent of reversibili ty and defect count activity during stress and rest were similar in patient s 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 collat erals. These data lend support to the premise that collateral circulation i s rather insufficient to prevent stress-induced ischemia, although it can p reserve myocardial viability.