Cardiac magnetic resonance imaging improves prognostic stratification of patients with ST-elevation myocardial infarction and preserved ejection fraction

AIMS: To evaluate the prognostic validity of clinical risk factors as well as infarct characterization and myocardial deformation by cardiac magnetic resonance (CMR) in ST-elevation myocardial infarction (STEMI) patients with preserved left ventricular ejection fraction (LVEF) following primary percutaneous coronary intervention (PCI). METHODS AND RESULTS: This multicentre, individual patient-data analysis from two large CMR trials included 1247 STEMI patients. Cardiac magnetic resonance examinations were conducted 3 [interquartile range (IQR) 2–4] days after PCI. LVEF, infarct size, microvascular obstruction (MVO), and myocardial strain values were measured. Primary endpoint was defined as composite of major adverse cardiovascular events (MACE) including death, re-infarction, and congestive heart failure. A preserved LVEF (defined as LVEF ≥50%) was observed in 724 patients (=58%). In the overall cohort, 97 patients experienced a MACE event [follow-up time 12 (IQR 12–13) months], and 34 MACE events occurred in the group with preserved LVEF (5% vs. 12% incidence rate in patients with LVEF < 50%). TIMI risk score [hazard ratio (HR) 1.28, 95% confidence interval (CI) 1.02–1.59; P = 0.03] and female gender (HR 2.24, 95% CI 1.10–4.57; P = 0.03) emerged as independent clinical determinants of MACE in the patient group with preserved LVEF. Among CMR parameters, the presence of MVO (HR 2.39, 95% CI 1.05–5.46; P = 0.04) and reduced global longitudinal strain (GLS; HR 1.12, 95% CI 1.02–1.23; P = 0.02) independently predicted MACE in the LVEF-preserved population. The addition of MVO and GLS to the clinical prognostic markers (TIMI risk score, female gender) increased (P = 0.02) the prognostic validity [AUC 0.76 (95% CI 0.73–0.79)] compared to the clinical markers alone [AUC 0.65 (0.62–0.69)]. CONCLUSION: In contemporary treated STEMI patients showing preserved LVEF, a CMR-based risk prediction approach assessing MVO and GLS provided strong prognostic value that was incremental to clinical outcome parameters.