Association between the insufficient improvement of the quantitative flow ratio and worsening outcomes in ST-segment elevated myocardial infarction: a multicentre prospective cohort study

Improved coronary physiological function after percutaneous coronary intervention (PCI) has been shown to improve prognosis in stable ischaemic heart disease, but has not yet been explored in ST-segment elevated myocardial infarction (STEMI). The study sought to determine whether an improvement in the quantitative flow ratio (QFR) could improve the prognosis of STEMI patients undergoing primary PCI. Patients diagnosed with STEMI who were receiving primary PCI were recruited for the study. Those with thrombolysis in myocardial infarction (TIMI) flow 0.25, N=183). Patients with a lower ΔQFR had a relatively higher rate of MI/AHF (10.5% 4.4%, P=0.019) and AHF (7.2% 2.7%, P=0.044). A lower ΔQFR was significantly associated with a higher incidence of MI/AHF [hazard ratio (HR) =2.962, 95% confidence interval (CI): 1.358-6.459, P=0.006, respectively] after adjusting for potential confounders. Pre-stent angiographic microvascular resistance [odds ratio (OR) =1.027, 95% CI: 1.022-1.033, P