The prognostic significance of angioIMR in patients with acute myocardial infarction: systematic review and meta-analysis

Abstract Background Microvascular injury is a key determinant of adverse clinical outcomes following acute myocardial infarction (AMI), yet its prognostic significance remains incompletely understood. While invasive index of microcirculatory resistance (IMR) has been well studied, the utility of angioIMR, a non-pressure wire-based alternative, is an emerging tool that warrants further investigation. Purpose This meta-analysis aims to evaluate the prognostic impact of post-primary PCI angioIMR on major adverse cardiovascular events in AMI patients. Methods We conducted a systematic literature search for studies assessing post-PCI IMR in patients with AMI. We recorded the year of publication, type of AMI, method of IMR assessment, the used cutoffs, patients’ age, sex, cardiovascular risk factors, and follow-up duration. The outcomes of interest were all-cause mortality (ACM), cardiovascular mortality (CVM), hospitalization for HF (HHF), reinfarction, target-vessel revascularization (TVR), as well as combined endpoints (ACM+HHF, CVM+HHF) at maximal follow-up. We extracted the event rates for those endpoints for the groups with and without abnormal IMR, as defined by each study. Pooling of the hazard ratios was conducted according to a common effects model. I2 was chosen as the measure of between-study heterogeneity, with values exceeding 50% being considered significant. Results We identified a total of 407 studies, of which 8 were ultimately selected for data extraction and inclusion in the meta-analysis after screening of title/abstract/full-text (Figure 1). AngioIMR cutoffs varied across the studies, with most considering values above 40 as abnormal. The mean age did not exceed 68 years in both groups, with the majority of the subjects being male. The rates of hypertension, diabetes mellitus, and dyslipidemia were grossly similar between the intervention and the control group. The follow-up duration ranged from 1 to 10 years. According to the results of the meta-analysis, compared to the normal angioIMR group, the presence of an abnormal angioIMR was associated with higher rates of the combined endpoints of ACM+HHF and CVM+HHF, as well as with their individual components (Figure 2). There was evidence of moderate between-study heterogeneity in the meta-analyses of CVM (I2=62%) and TVR (I2=66%). Conclusion This meta-analysis suggests that post-PCI angioIMR is associated with an adverse prognosis in patients with AMI. These findings further support the prognostic potential of this non-pressure wirse-based markers of microcirculatory function in this high-risk subgroup.Figure 1 Figure 2