An Association between Collateral Blood Flow and Myocardial Viability in Patients with Recent Myocardial Infarction

We hypothesized that successful reperfusion of an occluded infarct-related coronary artery even late after acute myocardial infarction would result in improved regional wall motion and that such improvement might be related to the presence of collateral blood flow within the infarct bed. We assessed regional wall motion by two-dimensional echocardiography at base line and one month after angioplasty was attempted in the occluded infarct-related artery in 43 patients who had had a myocardial infarction two days to five weeks earlier. A wall-motion score was assigned to each patient on a five-point scale (from 1 [normal function] to 5 [dyskinesia]). The percentage of the infarct bed perfused by collateral flow was assessed with myocardial contrast echocardiography. In the 41 patients who had abnormal wall motion at base line, improvement in function was noted in 25 (78 percent) of the 32 in whom angioplasty was successful, as compared with only 1 (11 percent) of the 9 in whom it was unsuccessful (P<0.001). The percentage of the infarct bed supplied by collateral flow at base line was directly correlated with wall function and inversely correlated with the wall-motion score one month after successful angioplasty (r = -0.64, P<0.001). Among the patients in whom angioplasty was successful, the 23 in whom >50 percent of the infarct bed was supplied by collateral flow had better wall motion (P<0.001) and greater improvement in wall motion at one month (P = 0.004) than the 9 in whom ≤50 percent of the bed was supplied by collateral flow. The degree of improvement in function was not influenced by the length of time between the infarction and the attempted angioplasty. The myocardium remains viable for a prolonged period in many patients with acute infarction and an occluded infarct-related artery. Viability appears to be associated with the presence of collateral blood flow within the infarct bed. (N Engl J Med 1992; 327:1825–31.), BESIDES the amount of myocardium at risk, the two main determinants of both infarct size and the amount of viable myocardium after acute coronary occlusion are the duration of occlusion and the extent of collateral blood flow within the occluded vascular bed.^{1 , 2} Whereas the effect of the duration of coronary occlusion has been extensively studied,^{3 4 5 6 7 8} previous attempts to assess the importance of collateral vessels in patients with acute myocardial infarction have been limited by the techniques used.^{9 10 11 12} Coronary angiography, the method most often used to assess collateral blood flow, can identify only vessels greater than 100 μm in diameter,¹³ whereas…