Novel application of quantitative flow ratio for predicting microvascular dysfunction after ST‐segment‐elevation myocardial infarction

Abstract Objectives This study evaluated quantitative flow ratio (QFR) to predict microvascular dysfunction (MVD) in patients with ST‐segment elevation myocardial infarction (STEMI). Background QFR is a novel approach for the rapid computation of fractional flow reserve based on three‐dimensional quantitative coronary angiography. We hypothesized that QFR computation could be used to predict MVD after STEMI. Methods Indexes such as contrast‐flow QFR (cQFR), fixed‐flow QFR (fQFR), and hyperemic flow velocity (HFV) were calculated in 130 STEMI patients with culprit lesion with ≥50% diameter stenosis and TIMI flow grade 2/3 in the spontaneously recanalized culprit artery on initial angiography. MVD was defined as microvascular obstruction determined by contrast‐enhanced cardiac magnetic resonance at a median of 5 days after percutaneous coronary intervention. Results Patients were divided into the MVD group (76/130, 58.5%) and non‐MVD group (54/130, 41.5%). Patients with MVD had higher cQFR‐fQFR value (0.080 ± 0.058 vs. 0.038 ± 0.039, p < .001) and lower modeled HFV (0.096 ± 0.044 vs. 0.144 ± 0.041 m/s, p < .001). Receiver operator characteristic curve analysis revealed that both the cQFR‐fQFR value (area under the curve, AUC = 0.716, p < .001) and modeled HFV (AUC = 0.805, p < .001) had high specificity and positive predictive value to predict MVD. In multivariable logistic analysis, cQFR‐fQFR was identified as an independent predictor of MVD (odds ratio = 9.800, p < .001). Conclusions This proof‐of‐concept study suggested that QFR computation may be a useful tool to predict MVD after STEMI (Trial Registration:NCT03780335).