Cardiac magnetic resonance imaging improves prognostic stratification of patients with ST-elevation myocardial infarction and preserved ejection fraction
Abstract 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 multicenter, individual patient-data analysis from two large CMR trials included 1247 STEMI patients. CMR 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%, versus 12% incidence rate in patients with LVEF<50%). TIMI risk score (hazard ratio[HR]:1.28[95%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, 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.