Novel Acute Collateral Flow Index in Patients With Total Coronary Artery Occlusion During ST-Elevation Myocardial Infarction

Abstract

The effect of collaterals to occluded coronary arteries during ST-elevation myocardial infarction (STEMI) is unclear. The conventional CVP-based formula to calculate collateral flow index during STEMI yields values higher than in elective patients, which prompted derivation of a modified formula, pertinent in STEMI when left ventricular mean diastolic pressure (LVMDP) is the extravascular pressure limiting collateral flow. We aimed to evaluate this new LVMDP-based acute collateral flow index (ACFI). The pressure distal to coronary artery occlusion (P(d)) was measured during intervention in 111 consecutive STEMI patients, 67 (61%) of whom underwent primary intervention, followed for 58 months. ACFI (0.18 ± 0.17, median 0.15) correlated with both P(d) and collateral grade (P<0.0001). Higher creatine kinase levels and white cell counts were measured in the lowest ACFI tertile compared with the highest tertile group (P<0.012). ACFI correlated slightly with early regional but not with global left ventricular ejection fraction or with long-term coronary events and mortality. The ACFI is appropriate for evaluating collateral function during STEMI. Collateral flow during STEMI may marginally limit myocardial damage but had no effect on left ventricular contraction or long-term mortality, most likely because of the low flow provided by emerging collaterals and the high proportion of patients undergoing intervention before the beneficial effect of collaterals could be realized.