MYOCARDIAL VIABILITY IN ASYNERGIC REGIONS SUBTENDED BY OCCLUDED CORONARY-ARTERIES - RELATION TO THE STATUS OF COLLATERAL FLOW IN PATIENTS WITH CHRONIC CORONARY-ARTERY DISEASE

Objectives. This study aimed to determine whether angiographically vis ualized collateral vessels in patients with chronic coronary artery di sease imply the presence of viable myocardium in asynergic regions sub tended by completely occluded coronary arteries. Background. Patients with chronic coronary artery disease who are being considered for reva scularization frequently exhibit angiographically visualized collatera l vessels to completely occluded coronary arteries supplying severely asynergic myocardial regions. However, little is known about the relat ion between angiographic collateral flow and myocardial viability in t hese patients. Methods. We studied 42 patients with 78 completely occl uded coronary arteries supplying asynergic territories. Angiographic c ollateral vessels were interpreted as absent (grade 1) in 14 patients, minimal (grade 2) in 27 and well developed (grade 3) in 37. Myocardia l viability was determined with positron emission tomography using nit rogen-13 (N-13) ammonia and fluorine-18 (F-18) deoxyglucose for assess ment of regional perfusion and glucose uptake, respectively. Positron emission tomographic patterns were interpreted as mismatch (perfusion defect with enhanced F-18 deoxyglucose uptake); transmural match (seve re concordant reduction or absence of both perfusion and F-18 deoxyglu cose uptake) or nontransmural match (mild to moderate concordant reduc tion of both perfusion and F-18 deoxyglucose uptake). Results. There w as no significant correlation (p = 0.14) between the severity of perfu sion deficit assessed by positron emission tomography and the collater al grade. The extent of mismatch was unrelated to either the presence or the magnitude of collateral vessels. Conversely, with increasing co llateral vessels from grade 1 to 3, the total extent of positron emiss ion tomographic match remained similar, whereas the ratio of transmura l to nontransmural match decreased. Myocardial viability was usually p resent in severely hypokinetic regions (82%). It was lower in akinetic -dyskinetic regions (49%). Of the 64 regions with angiographic collate ral vessels, 37 (58%) (95% confidence interval [CI] 46% to 70%) showed positron emission tomographic mismatch. In contrast, 7 (50%) of 14 (9 5% CI 24% to 76%) regions without collateral vessels on angiography ex hibited positron emission tomographic mismatch. The presence of angiog raphically visualized collateral vessels was a sensitive (84%) but not specific (21%) marker of viability. Conclusions. In patients with chr onic coronary artery disease, angiographically visualized collateral v essels to asynergic myocardial regions subtended by occluded coronary arteries do not always imply the presence of viable myocardium, sugges ting that revascularization may not always provide a functional benefi t.