We investigated the influence of collateral flow on restenosis in 156 consecutive acute myocardial infarction (AMI) patients treated with primary angioplasty within 12 hr of symptom onset. Collateral flow was quantitatively assessed using the pressure-derived fractional collateral flow (PDCF) index. Follow-up angiography was performed at 6 months. The patients were classified into two groups according to the PDCF index: group I (PDCF index > 24%; n = 55) with good collaterals and group II (PDCF index < or = 24%; n = 101) with poor collaterals. Baseline characteristics were similar between the two groups, with the exception of peak levels of creatine kinase, angiographic collaterals, and TIMI flow 3 after intervention. The binary restenosis rate was 31.8% in group I and 32.9% in group II (P = NS). Use of the stents was the only independent predictor of binary restenosis. In conclusions, well-developed collaterals measured by PDCF may not predict restenosis following primary angioplasty for AMI.

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