Influence of coronary collateral blood flow on the development of exertional ischemia and Q wave infarction in patients with severe single-vessel disease.

The functional significance of coronary collateral flow from a nonobstructed supply artery was studied in 121 patients with severe (greater than or equal to 80%) single-vessel disease, 64 with and 57 without Q wave infarction. All patients underwent exercise thallium imaging and coronary angiography. On angiography, collateral flow was present in 85% of 74 occluded arteries compared with only 17% of 47 arteries with subtotal obstruction (p less than .001). Collateral flow was not seen in arteries with lesions of less than 90% obstruction. Collateral flow was present in 100% of 29 occluded arteries in patients without Q wave infarction compared with only 76% of 45 occluded arteries with Q wave infarction (p less than .005). Clinical variables did not correlate with collateral flow. Collateral flow did not prevent ischemia on exercise thallium imaging in patients without Q wave infarction: 30 of 33 (91%) with collateral flow had reversible thallium defects compared with 24 of 24 (100%) without collateral flow (p = NS). In patients with Q wave infarction, partially reversible exercise thallium defects (peri-infarctional ischemia) were more common with flow to the area from either subtotal obstruction (73%) or collateral flow (45%) than with no flow from total occlusion (27%; p = .05). In patients with severe single-vessel disease the presence of collateral flow is principally determined by coronary occlusion. Collateral flow may protect from Q wave infarction but does not prevent exercise ischemia on thallium imaging.