Delays in Presentation in Patients With Acute Myocardial Infarction During the COVID-19 Pandemic

Background: Coronary microvascular dysfunction (CMD) is a common complication of ST‐segment–elevation myocardial infarction (STEMI) and can lead to adverse cardiovascular events. Whether CMD after STEMI is associated with functional left ventricular remodeling (FLVR) and diastolic dysfunction, has not been investigated. Methods and Results: This is a nonrandomized, observational, prospective study of patients with STEMI with multivessel disease. Coronary flow reserve and index of microcirculatory resistance of the culprit vessel were measured at 3 months post‐STEMI. CMD was defined as index of microcirculatory resistance ≥25 or coronary flow reserve <2.0 with a normal fractional flow reserve. We examined the association between CMD, LV diastolic dysfunction, FLVR, and major adverse cardiac events at 12‐month follow‐up. A total of 210 patients were enrolled; 59.5% were men, with a median age of 65 (interquartile range, 58–76) years. At 3‐month follow‐up, 57 patients (27.14%) exhibited CMD. After 12 months, when compared with patients without CMD, patients with CMD had poorer LV systolic function recovery (−10.00% versus 8.00%; P <0.001), higher prevalence of grade 2 LV diastolic dysfunction (73.08% versus 1.32%; P <0.001), higher prevalence of group 3 or 4 FLVR (11.32% versus 7.28% and 22.64% versus 1.99%, respectively; P <0.001), and higher incidence of major adverse cardiac events (50.9% versus 9.8%; P <0.001). Index of microcirculatory resistance was independently associated with LV diastolic dysfunction and adverse FLVR. Conclusions: CMD is present in ≈1 of 4 patients with STEMI during follow‐up. Patients with CMD have a higher prevalence of LV diastolic dysfunction, adverse FLVR, and major adverse cardiac events at 12 months compared with those without CMD. Registration: URL: https://www.clinicaltrials.gov ; Unique Identifier: NCT05406297.