Pressure-derived fractional collateral blood flow (PDCF) determines the severity of myocardial perfusion defect following primary angioplasty (PA) in acute myocardial infarction (AMI)

We tested the hypothesis that PDCF may be a major determinant of the severity of myocardial perfusion defect after reperfused AMI. Patients were 64 with a first AMI who were treated with PA (pain onset < 12 hrs). PDCF was determined using measurement of mean aorta pressure (Pao), the distal coronary pressure during the balloon occlusion (Pocc) and the right atrial pressure (RA): PDCF =(Pocc-RA) / (Pao-RA) X 100. Tl-201 uptake was scored from 0 (normal) to 4 (absent uptake) on reinjection images. The mean thallium score index (TSI) was calculated by averaging Tl-201 scores within infarct territory. Successful restoration of the infarct artery patency (TIMI ≥2) was achieved in all patients. A total of 381 segments were hypo or akinetic, and a mean TSI was 2.14±0.87. PDCF (p<0.01) and the presence of TIMI 3 after PA ( p<0.05) were identified as determinants of mean TSI using univariate analysis. Time to reperfusion, and angiographic collaterals were not found to be predictive of mean TSI. Multivariate analysis revealed that PDCF was the only independent predictor of TSI (r=0.38, p<0.01). Collateral flow during AMI may play a crucial role in preserving microcirculation of the infarct-related myocardium