Prognostic Significance and Determinants of Myocardial Salvage Assessed by Cardiovascular Magnetic Resonance in Acute Reperfused Myocardial Infarction

Abstract

OBJECTIVES The aim of the study was to determine the prognostic significance and determinants of myocardial salvage assessed by cardiovascular magnetic resonance (CMR) in reperfused ST-segment elevation myocardial infarction. BACKGROUND In acute myocardial infarction, CMR can retrospectively detect the myocardium at risk and the irreversible injury. This allows for quantifying the extent of salvaged myocardium after reperfusion as a potential strong end point for clinical trials and outcome. METHODS We analyzed 208 consecutive ST-segment elevation myocardial infarction patients undergoing primary angioplasty <12 h after symptom onset. T2-weighted and contrast-enhanced CMR was used to calculate the myocardial salvage index (MSI). Patients were categorized into 2 groups defined by the median MSI. The primary end point of the study was occurrence of major adverse cardiovascular events defined as death, reinfarction, and occurrence of new congestive heart failure within 6 months after the index event. RESULTS The median MSI was 48 (interquartile range 27 to 73). Major adverse cardiovascular events were significantly lower in the MSI >or= median group (2.9% vs. 22.1%, p < 0.001). The stepwise Cox proportional hazards model revealed that the MSI was the strongest predictor of major adverse cardiovascular events at 6-month follow-up (p < 0.001). All prognostic clinical (symptom onset to reperfusion), angiographic (Thrombolysis In Myocardial Infarction flow grade before angioplasty), and electrocardiographic (ST-segment resolution) parameters showed significant correlations with the MSI (p < 0.001 for all). CONCLUSIONS This study for the first time demonstrates that the MSI assessed by CMR predicts the outcome in acute reperfused ST-segment elevation myocardial infarction. Therefore, MSI assessment has important implications for patient prognosis as well as for the design of future trials intended to test new reperfusion therapy efficacy. (Myocardial Salvage Assessed by Cardiovascular Magnetic Resonance-Impact on Outcome; NCT00952224).