The Predictive Effects of ECG and QFR in the Detection of Microvascular Obstruction in Patients With STEMI After PPCI

Cardiac magnetic resonance (CMR) is an effective tool for evaluating microvascular obstruction (MVO). This study aimed to compare the predictive effects of noninvasive methods, specifically early ST-segment resolution (STR) and quantitative flow ratio (QFR) in the detection of MVO in patients with ST-segment elevation myocardial infarction (STEMI) after primary percutaneous coronary intervention (PPCI).

A prospective cohort study enrolled 208 consecutive patients with acutely reperfused STEMI. The degree of STR was calculated postprocedure and predischarge after reperfusion. QFR measurements were obtained based on angiography, while CMR was performed within a median time of 5 days after revascularization to determine the presence of MVO. Clinical factors were enrolled to predict the incidence of MVO.

There were 126 patients identified to suffer MVO according to CMR. The area under the curve (AUC) identified QFR is the best predictor (AUC: 0.784, p < 0.001). The effect of QFR significantly increased beyond the baseline risk model with net reclassification improvement (NRI) 0.3373 (0.003-0.6716, p = 0.048). The MVO/left ventricular (LV) mass is 1.42 ± 2.28 in 126 patients with MVO according to CMR. Regression analysis indicated that postoperative STR (β = -0.267, p = 0.001) was a significant predictor of MVO/LV mass. Higher STR usually means lower infarct size, better cardiac systolic and diastolic function. Predischarge STR is closely correlated with the infarct size after 6-month follow-up (r = -0.509, p < 0.001).

In STEMI patients after PPCI, QFR exhibited a superior predictive capability for the occurrence of MVO. STR demonstrated a reliable predictive ability for MVO/LV mass in MVO populations, and exhibited correlations with heart function and infarct size during long-term follow-up.