Microvascular integrity has been associated with the clinical outcomes in acute myocardial infarction (AMI). The present study was conducted to determine the value of many microvascular indexes assessed by an intracoronary (IC) pressure/Doppler wire in AMI following primary PCI for detecting viable myocardium by comparing with the ¹⁸F-fluorodeoxyglucose uptake rate (%FDG uptake) on positron-emission tomography (PET).

We studied 35 patients who had their first AMI (age: 56±12, male: 30). After primary PCI, the TMPG (TIMI myocardial perfusion grade) was assessed. We measured the coronary flow reserve (CFR), the diastolic deceleration time (DDT), the coronary wedge pressure (Pcw), the Pcw/Pa (mean aortic pressure) and the hyperemic microvascular resistance index (hMVRI) by an IC Doppler/pressure wire. ¹⁸FDG PET scan was obtained at 7 days after the primary PCI; viable myocardium was defined that the %FDG uptake was more than 50% in infarct-related myocardium.

There were significant correlations between TMPG, CFR, Pcw, Pcw/Pa, DDT, hMVRI and %FDG uptake (r=0.651, p<0.001; r=0.386, p=0.020; r=-0.388, p=0.021; r=-0.473, p=0.004; r=0.589, p<0.001; r=-0.442, p=0.008, respectively). The best cutoff values and area under curves (AUC) of the CFR, Pcw, Pcw/Pa, DDT and hMVRI for 50% FDG uptake were 1.8 (0.737), 27 mmHg (0.600), 0.33 (0.660), 600 msec (0.802) and 2.55 mmHg·cm^-1·sec (0.768), respectively. The DDT had a significantly higher AUC than that of Pcw (p=0.029) and it was an independent index to predict the myocardial viability (p=0.011).

DDT was the most reliable hemodynamic microvascular index that was assessed within 24 hours following primary PCI for predicting the viable myocardium in AMI patients.