Outcomes of endovascular treatment for myocardial infarction and different phenotypes of coronary microvascular obstruction syndrome (slow-flow/no-reflow)

Objective. To study the outcomes of percutaneous coronary interventions (PCI) in patients with myocardial infarction (MI) and different phenotypes of coronary microvascular obstruction (CMVO). Material and methods. A single-center cohort study enrolled patients with type 1 MI who underwent PCI and developed CMVO (TIMI flow grade<3 or Myocardial blush grade<2 or no ST-segment resolution after PCI). Using the methodology by Frolov A.A. (2023), we classified patients depending on CMVO phenotypes. Patients with moderate coronary thrombosis (Thrombus Burden Classification grades 0—3) were assigned to atheroembolic phenotype. Among other patients with severe thrombosis (grades 4—5), those younger than 67 years were classified as microthromboembolic», those aged ≥67 years — age-associated. The median follow-up was 1036 880; 1371 days. We analyzed survival rates across different phenotypes (Log-rank test) and performed multivariate analysis of mortality risk (weighted Cox regression). Results. A total of 190 patients were included. In-hospital mortality was 4.7% (n=9), and 29 (15.3%) ones died after discharge. Thus, the overall mortality rate was 20% (n=38). The probability of survival was comparable in microthromboembolic and atheroembolic phenotypes (0.78 and 0.79, respectively), but it was the lowest in age-associated phenotype (0.46, p<0.001). Multivariate analysis showed that age-associated phenotype was a predictor of death (hazard ratio 4.02, 95% confidence interval 1.56—10.3, p=0.004). Conclusion. Patients with MI and PCI complicated by distal thrombo- or atheroembolism have significant but comparable risk of death over the following years. Patients with age-associated phenotype have the worst prognosis.