Coronary Angiography–Derived Index of Microcirculatory Resistance Associated with New-Onset Atrial Fibrillation in Patients with STEMI

Background The coronary angiography–derived index of microcirculatory resistance (caIMR) can effectively assess coronary microvascular dysfunction (CMD) in patients with ST-segment elevation myocardial infarction (STEMI). This study aimed to explore the role of caIMR in the occurrence of new-onset atrial fibrillation (NOAF) in patients with STEMI. Materials and Methods This was a single-centre retrospective clinical observational study. Patients diagnosed with STEMI from September 2019 to December 2022 were included. caIMR was calculated using computational flow and pressure simulations. During admission, suspicious heart rhythm was recorded by electrocardiogram (ECG) monitoring, and NOAF was confirmed by an immediate 12-lead ECG. Results A total of 739 patients were enrolled, including 57 (7.7%) with NOAF. caIMR was significantly correlated with microvascular obstruction (R=0.604, P<0.001) and infarct size (R=0.514, P<0.001). After adjusting for potential confounding factors, the results showed that caIMR (odds ratio=1.058; 95% confidence interval: 1.035-1.083, P<0.001) was an independent risk factor for NOAF in STEMI patients. Receiver operating characteristic analysis showed that the area under the curve of caIMR for predicting NOAF was 0.716. Compared with the caIMR < 27.35 U group, the caIMR ≥ 27.35 U group had higher high-sensitivity troponin T and N-terminal pro-B-type natriuretic peptide levels. When caIMR was added to the model, the reclassification and discriminant abilities improved significantly. Conclusions Higher caIMR was an independent risk factor for NOAF in patients with STEMI. The caIMR had high specificity and sensitivity for predicting NOAF in STEMI patients. The integration of caIMR into clinical risk factors showed significantly increased predictability for NOAF in patients with STEMI.