Concurrent Microvascular and Infarct Remodeling After Successful Reperfusion of ST-Elevation Acute Myocardial Infarction

Abstract

Background-Connection between the course of microvascular and infarct remodeling processes over time after reperfused ST-elevation acute myocardial infarction has not been fully elucidated. The aim of this study is to investigate the association of temporal changes in hemodynamics of microcirculation in the infarcted territory and infarct size (IS) after primary percutaneous coronary intervention in patients with ST-elevation acute myocardial infarction. Methods and Results-Thirty-five patients admitted with ST-elevation acute myocardial infarction undergoing primary percutaneous coronary intervention were enrolled in the study. Coronary flow reserve (CFR), index of microvascular resistance (IMR), and IS were assessed 2 days after primary percutaneous coronary intervention and at the 5-month follow-up. The predictors of the 5-month IS were the baseline values of IS (␤ϭ0.6, PϽ0.001), IMR (␤ϭ0.280, Pϭ0.013), and CFR (␤ϭϪ0.276, Pϭ0.017). There were significant correlations between relative change in IS and relative change in measures of microvascular function (IS and CFR [rϭϪ0.51, Pϭ0.002]); IS and IMR ([rϭ0.55, Pϭ0.001]). In multivariate model, relative changes in IMR (␤ϭ0.552, Pϭ0.001) and CFR (␤ϭϪ0.511, Pϭ0.002) were the only predictors of relative change in IS. In patients with an improvement in IMR Ͼ33%, the mean IS decreased from 32.3Ϯ16.9% to 19.3Ϯ14% (Pϭ0.001) in the follow-up. Similarly, in patients with an improvement in CFR Ͼ41%, the mean IS significantly decreased from 29.9Ϯ20% to 15.8Ϯ12.4% (Pϭ0.003). But in patients with an improvement in IMR and CFR, which were below than the mean values, IS did not significantly decrease during the follow-up. Conclusions-Improvement in microvascular function in the infarcted territory is associated with reduction in IS after reperfused ST-elevation acute myocardial infarction. This link suggests that further investigations are warranted to determine whether therapeutic protection of microvascular integrity results in augmentation of infarct healing. (Circ Cardiovasc Interv. 2010;3:208-215.)Key Words: myocardial infarction Ⅲ microcirculation Ⅲ reperfusion Ⅲ remodeling E picardial coronary artery occlusion is accompanied by microvascular damage during the course of ST-elevation acute myocardial infarction (STEMI). Excessive microvascular destruction is associated with greater infarct size (IS), worse myocardial function, and poor clinical outcome after STEMI. [1][2][3][4][5] In the models of reperfused acute myocardial infarction (AMI), it has been demonstrated that there is a causal connection between the amount of microvascular destruction and myocardial damage. 6 This proven concordance implies that therapeutic approaches should focus on preventing microvascular damage at acute phase of STEMI and stimulating reconstitution of microcirculation during follow-up to improve long-term myocardial healing and survival. Accordingly, our group recently reported that in patients with STEMI undergoing primary percutaneous coronary intervention (pPCI), (1) adjunctive intrac...

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