Role of collateral circulation in the acute phase of ST-segment-elevation myocardial infarction treated with primary coronary intervention

Aims The rote of collateral flow in the first hours of infarction remains unclear. Our aim was to determine whether the presence of coronary collateral flow, as evidenced by angiography, has a beneficial effect on infarct size and left ventricular function in acute myocardial infarction (MI) treated by means of early percutaneous coronary intervention (PCI). Methods Between 1994 and 2001, 1059 patients with acute MI treated with primary PCI, TIMI (Thrombolysis in Myocardial Infarction) 0 or 1 flow at first contrast injection and technically adequate angiograms for collateral flow detection were analysed. Results Comparison of collateral flow grades 0, 1, and 2/3 showed that increased collateral flow was associated with a lower incidence of Killip class greater than or equal to2 at presentation (12% vs. 10% vs. 3%, p for trend 0.02), less need for intra-aortic balloon pumping after PCI (17% vs. 13% vs. 5%, p for trend 0.005), better myocardial blush grade (MBG) in infarcts related with the left anterior descending coronary artery (LAD) (MBG3: 14% vs. 18% vs. 34%, p for trend 0.01), and smaller enzymatic infarct size (cumulative lactate dehydrogenase release 36 h after symptom onset [LDHQ(36)]) (1932 1531 U/l vs. 1870 1458 U/l vs. 1217 762 U/l, p for trend 0.041). These beneficial effects were particularly evident in LAD-related infarcts. Conclusion The presence of angiographicalty detectable collaterals has a protective effect on enzymatic infarct size and pre- and postintervention haemodynamic conditions in patients with acute MI treated by primary PCI, in particular when Rentrop grade 2/3 is present and the LAD is involved in the infarct. (C) 2004 The European Society of Cardiology. Published by Elsevier Ltd. All rights reserved.