The relationships between cardiovascular magnetic resonance imaging variables of acute myocardial infarction and both left ventricular dysfunction and immediate postreperfusion ST segment recovery

Objective: The aim of this study is to explore the relationships between cardiovascular magnetic resonance imaging (CMR)-determined variables of acute myocardial infarction and both left ventricular (LV) dysfunction and immediate postreperfusion ST segment recovery. Methods: In 79 patients with first acute myocardial infarction, 8 different ST segment recovery (STR) variables were measured 30 and 60 minutes after percutaneous coronary intervention. Cardiovascular magnetic resonance imaging was performed 5 +/- 2 and 104 +/- 11 days after admission. Using k-means cluster analysis, 3 CMR risk groups for LV dysfunction (low LV ejection fraction at baseline and follow-up) were identified based on combinations of infarct size (IS), infarct transmurality, and microvascular obstruction. Stepwise discriminant analysis was used to determine which STR variable best discriminated between CMR risk groups. Results: Baseline LV ejection fraction improved in all groups but remained lowest in the high-risk group (41% +/- 7% and 44% +/- 6%), as compared with the intermediate (51% +/- 5% and 56% +/- 5%) and low-risk groups (56% +/- 7% and 58% +/- 5%). Infarct size was significantly different among the groups (34% +/- 5%, 19% +/- 4%, and 6% +/- 4%; P <.001) and mainly determined the effect on LV dysfunction. Of all STR variables, worst lead residual ST deviation 30 minutes after reperfusion accurately discriminated between the high- and combined low-/intermediate risk groups. Conclusion: Worst lead residual ST deviation 30 minutes after reperfusion allows accurate identification of patients at high risk for LV dysfunction, which was mainly related to IS rather than transmurality or microvascular obstruction.