Epicardial fat volume assessment and strain analysis by cardiac magnetic resonance: a novel method for evaluating microcirculation dysfunction after myocardial infarction.

Background: In the context of acute ST-segment elevation myocardial infarction (STEMI), epicardial fat volume (EFV) has a significant impact on the formation of microvascular obstruction (MVO). This study aimed to quantitatively measure the EFV and myocardial strain parameters by cardiac magnetic resonance (CMR) and to explore their relationship with the presence or absence of mcrocirculation dysfunction after myocardial infarction. Methods: This was a retrospective study. From June 2022 to December 2023, 56 consecutive patients diagnosed with acute STEMI who underwent percutaneous coronary intervention (PCI) were selected from The First Affiliated Hospital of Bengbu Medical University. Patients were divided into two groups based on the presence of MVO group and the non-MVO (NMVO) group, with 22 cases (39%) and 34 cases (61%) respectively. The characteristics of the infarction were assessed by delayed enhancement with gadolinium. Based on standard cine images, the global circumferential strain (GCS), global radial strain (GRS), and global longitudinal strain (GLS) of the left and right ventricles were evaluated using CMR feature tracking (CMR-FT) imaging. The volume of EFV was quantified along the short-axis slices of the left and right ventricles at the end of diastole by CMR imaging. The differences in baseline characteristics, EFV, and myocardial strain parameters between the groups were compared using Pearson or Spearman correlation analysis. The specificity and sensitivity of myocardial strain parameters in predicting MVO were obtained using receiver operating characteristic (ROC) curves. The predictive factors for MVO were analyzed using univariate and multivariate logistic regression analyses. Results: A total of 56 patients were selected, with an average age of 59.84±12.37 years, including 42 males (75%) and 14 females (25%). There was a statistically significant difference in EFV between the MVO group and the NMVO group (P<0.001). The prediction model for MVO based on EFV [area under the ROC curve (AUC): 0.856; 95% confidence interval (CI): 0.736-0.935; sensitivity: 77.27%; specificity: 91.18%], GLS (AUC: 0.929; 95% CI: 0.828-0.980; sensitivity: 90.90%; specificity: 94.12%), GCS (AUC: 0.770; 95% CI: 0.638-0.872; sensitivity: 86.36%; specificity: 61.76%), GRS (AUC: 0.789; 95% CI: 0.659-0.886; sensitivity: 90.19%; specificity: 70.59%). The left ventricular ejection fraction in the MVO group was lower than that in the NMVO group (P=0.001). The GLS, GRS, and GCS in the MVO group were significantly lower than those in the NMVO group (P<0.001). Correlation analysis found that EFV (r=0.602, P<0.001), GLS (r=0.726, P<0.001), GCS (r=0.457, P<0.001) was significantly positively correlated with postoperative myocardial infarction with mcrocirculation obstruction, while GRS (r=-0.486, P<0.001) were negatively correlated with postoperative myocardial infarction with mcrocirculation obstruction. Conclusions: After myocardial infarction, there is more EFV in the presence of mcrocirculation dysfunction, and the local myocardial function is reduced more. Monitoring EFV plays a significant role in the early anti-lipid treatment strategy for patients with MVO.