Prognostic impact of persistent microvascular obstruction on cardiac magnetic resonance after STEMI: A systematic review and meta-analysis

Background Microvascular obstruction (MVO) frequently occurs after primary percutaneous coronary intervention (PCI) in patients with ST-segment elevation myocardial infarction (STEMI) and can be classified as transient or persistent based on its resolution on follow-up cardiac magnetic resonance (CMR) imaging. This meta-analysis aims to compare the prognostic significance of persistent MVO versus transient MVO and no MVO in patients with STEMI undergoing primary PCI. Methods we conducted a systematic search for cohort studies comparing persistent MVO to transient MVO or no MVO in patients with STEMI who underwent primary PCI and CMR imaging. For the meta-analysis, we used R software (version 4.5.0) with RStudio. Results We included seven cohort studies with a total of 2180 patients. Compared to transient MVO, persistent MVO was associated with significantly higher risks of MACE and death. Persistent MVO also demonstrated significantly lower LVEF and larger infarct size, but no significant association with recurrent MI or heart failure readmission. Compared to no-MVO, persistent MVO showed even stronger associations with adverse outcomes: MACE, death, heart failure readmission, lower LVEF, and larger infarct size. Conclusion Persistent MVO may be associated with worse clinical outcomes, adverse left ventricular remodeling, and larger infarct size compared to both transient MVO and no MVO. These findings support the role of follow-up CMR for risk stratification to identify high-risk population. However, the definition and timing of persistent MVO varied considerably across studies (1 week to 12 months), which introduce clinical heterogeneity highlighting the need for future studies with standardized definitions.