The Index of Microcirculatory Resistance Is Associated With New Onset of Atrial Fibrillation Following ST-Elevation Myocardial Infarction

Abstract

Background The index of microcirculatory resistance (IMR) is calculated from the mean transit time of bolus thermodilution during pharmacologically induced hyperemia. IMR has emerged as an invasive technique for measuring coronary microcirculation. The current study aimed to investigate the association of elevated IMR and new onset of atrial fibrillation (NOAF) in patients after the event of ST- elevation myocardial infarction (STEMI) [...]. Methods Our study comprised STEMI patients with multivessel disease who were 40 years or older. IMR was assessed after undergoing successful staged percutaneous coronary interventions (PCI) using a calibrated coronary physiology wire (Pressure Wire X; Abbott Vascular, Santa Clara, CA, United States). Patients were classified based on their IMR level. A high IMR was characterized as a value of 25 U or more. The primary outcome was the presence of atrial fibrillation 12 months after an ST-elevation [...]. Results 149 patients were classified as having a normal IMR, while 51 had an elevated IMR. Patients with elevated IMR levels were predominately female (32.9% vs. 62.7%; p < 0.001) and had a higher incidence of a history of diabetes mellitus (18.1 % vs. 43.1%; p < 0.001) than those with normal IMR levels. However, there were no differences in age or other risk factors between the two groups. NOAF at 12-month follow-up was significantly higher in the elevated IMR group (4.7% vs. 29.4%; p <0.001). [...]. Conclusion Our study demonstrates that in patients undergoing staged PCI after a STEMI event, an elevated IMR was associated with a higher incidence of atrial fibrillation at 12-month follow-up. [...].