Inflammation, Infarct Size and 10-Year Mortality in STEMI Patients Stratified by the ORBI Risk Score: A DANAMI-3 Sub-study

BACKGROUND: The ORBI Risk Score predicts in-hospital cardiogenic shock after primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI). Whether high-risk patients also have more systemic inflammation, larger infarcts and higher long-term mortality is not known. METHODS: In a DANAMI-3 sub-study, 1,574 STEMI patients without cardiogenic shock were classified as high (ORBI ≥8, n = 273) or low risk (n = 1,301). Inflammation was assessed by routine C-reactive protein (CRP), leukocyte count and neutrophil-to-lymphocyte ratio (NLR) within 72 hours of PCI, and admission mid-regional pro-adrenomedullin (MR-proADM). Infarct size was measured by cardiac magnetic resonance. Ten-year all-cause mortality was obtained from the Danish Civil Registration System. Cox models were adjusted for age, sex, comorbidity, kidney function and randomised allocation. RESULTS: High-risk patients had higher peak CRP (72 vs. 11 mg/L), leukocyte count (12.8 vs. 10.4 × 109/L), NLR (6.2 vs. 3.5) and MR-proADM (0.73 vs. 0.62 nmol/L; all p < 0.001), and larger infarcts (final infarct size 15.7% vs. 10.1% of left ventricular mass). Ten-year mortality was 41% vs. 20% (hazard ratio 2.56, 95% CI 2.05-3.20; adjusted 1.47, 1.16-1.85). The adjusted hazard ratio was 4.79 within 30 days and 1.27 after the first year. The score discriminated 10-year mortality less well than age alone (area under the curve 0.67 vs. 0.79). CONCLUSIONS: The ORBI Risk Score identifies STEMI patients with more inflammation, larger infarcts and higher mortality, especially in the first year. Beyond the first year the association was largely explained by age. Whether anti-inflammatory treatment benefits these patients is a question for randomised trials.