Coronary microvascular dysfunction mediates in-hospital adverse outcomes in ST-segment elevation myocardial infarction patients without standard modifiable cardiovascular risk factors

Background: Recent studies have demonstrated that patients with ST-segment elevation myocardial infarction (STEMI) without standard modifiable cardiovascular risk factors (SMuRF-less) experience worse in-hospital outcomes than those with standard modifiable cardiovascular risk factors (SMuRFs); however, the role of a critical pathological mechanism coronary microvascular dysfunction (CMVD) in this context remains unclear. Objectives: To investigate whether CMVD mediates the association between SMuRF-less status and in-hospital major adverse cardiovascular events (MACE). Methods: = 221). In-hospital MACE and post-procedural coronary angiography-derived index of microcirculatory resistance (caIMR) were compared between groups. Mediation analysis was performed to assess the mediating effect of post-procedural caIMR on the association between SMuRF-less status and in-hospital outcomes. Results: = 0.284, 95% bootstrap CI: 0.101-0.498). Conclusion: Elevated post-procedural caIMR, as a quantitative surrogate of CMVD, independently predicted in-hospital MACE and partially mediated the association between SMuRF-less status and adverse in-hospital outcomes in STEMI patients.