Effect of Pericardial Effusion Complicating ST-Elevation Myocardial Infarction as Predictor of Extensive Myocardial Damage and Prognosis

Pericardial effusion (PE) is a common complication following ST-elevation myocardial infarction (STEMI). However, the frequency and prognostic relevance of PE complicating STEMI are unknown. Aim of this study was to investigate the exact incidence, infarct characteristics, and the prognostic impact of moderate-to-large PEs detected by cardiac magnetic resonance (CMR) in patients with acute reperfused STEMI. In total, 780 patients with STEMI reperfused by angioplasty (<12 hours after symptom onset) were enrolled in this CMR study at 8 centers. CMR was completed in median 3 days after infarction using a standardized protocol. Central core laboratory-masked analysis for the presence of moderate-to-large PE was performed. The primary clinical end point was the occurrence of major adverse cardiac events (MACE) defined as composite of all-cause death, reinfarction, and new congestive heart failure within 12 months after the index event. A moderate-to-large PE was detected in 183 patients (24%). Patients with moderate-to-large PEs had significantly larger infarcts, less myocardial salvage, a larger extent of microvascular obstruction, higher incidence of intramyocardial hemorrhage, and more pronounced left ventricular dysfunction (p <0.001 for all). Significant predictors of a moderate-to-large PE were age, Thrombolysis in Myocardial Infarction flow before percutaneous coronary intervention, and infarct size. MACE rates were significantly higher in the PE group (p = 0.003) and a moderate-to-large PE was identified as a significant independent predictor for MACE (hazard ratio 3.12, 95% confidence interval 1.49 to 6.81; p = 0.003) together with Thrombolysis in Myocardial Infarction risk score and left ventricular ejection fraction. In conclusion, a moderate-to-large PE complicating STEMI is a common finding (almost 25%) and related to more severe infarcts with subsequent significantly increased MACE rates during 1-year follow-up. Consequently, a moderate-to-large PE is a marker of poor outcome in patients with STEMI.