Long-term Prognostic Implications of Microvascular Dysfunction Following Acute Coronary Syndrome: A Heterogeneity-focused Meta-analysis Based on a Random-effects Model

Microvascular dysfunction (MVD) after acute coronary syndrome (ACS) has become widely acknowledged as an important predictor of future clinical events, but lack of consistent evaluation of MVD and heterogeneity of patient material cause doubts about the real value of MVD as a risk indicator.In the context of this systematic review and meta-analysis, the effect of MVD on adverse long-term outcomes in patients with ACS was assessed using a random-effects model, given the anticipated heterogeneity.A total of 12 prospective and retrospective observational analysis studies involving 6,765 patients were included.Microvascular function was evaluated by both invasive and non-invasive modalities, such as IMR and CFR.Thus, impact of preserved microvascular function on MVD with the pooled HR of 2.01 (95% CI: 1.68-2.40)showed that MVD was associated with nearly two times higher risk of MACE, mortality, heart failure hospitalization, and recurrent myocardial infarction.Low to moderate level of heterogeneity (I = 58 %) was identified, which was in part attributed to subgroup analyses in terms of the method used in MVD assessment, ACS subtypes and follow-up period.The subgroup analyses carried out