ORBI risk score and inflammatory response in patients with acute ST-elevation myocardial infarction

Abstract Background The ORBI risk score was developed to predict in-hospital cardiogenic shock (CS) in patients with ST-elevation myocardial infarction (STEMI) [1]. An inflammatory response is seen in STEMI and may precede CS. The association between ORBI score and systemic inflammatory response is of interest both for improving risk assessment of CS but also for identifying potential therapeutic targets. Methods Using data from one center in the Third DANish Study of Optimal Acute Treatment of Patients With ST-Segment Elevation Myocardial Infarction (DANAMI 3) trial, the inflammat ory status was detected by peak C-reactive protein level (CRP) and white blood cell count (WBC) analyzed from blood samples taken within 96 hours from percutaneous coronary intervention (PCI). Patients were stratified into two ORBI risk groups: ‘Low’ (0-7) and ‘intermediate-high’ (>=8). Patients with CS at the time of PCI were not included, nor were those with out-of-hospital cardiac arrest. Logistic- and Cox Proportional Hazards regression was used to assess the association between ORBI risk groups and 1/ an above-median inflammatory status, and 2/ one-year mortality when combining risk group with inflammatory status. Results Of 1603 patients included, at least one 0–96-hour CRP was available in 631 (39.4%), and WBC in 628 (39.2%) of patients. Mortality at 96 hours was 1.3%. Median CRP and median WBC in the ‘intermediate-high’ ORBI risk group were 61.5 mg/L (interquartile range (IQR) 16-158) and 12 x 10^9/L (IQR 8.8-15.8) vs. 14 (IQR 5-38.8) and 10 (IQR 8.3-12.8) in the ‘low-risk’ group (p<0.001). ‘Intermediate-high’ ORBI score was associated with increased odds of an above-median CRP (OR 3.34, 95% confidence interval (CI) 2.20-5.18, p<0.001), as well as increased odds of an above-median WBC (OR 2.24, 95%CI 1.50-3.38, p<0.001) in univariate analyses. In patients having CRP levels above the median compared to those below, the median age was higher (66 years vs. 60 years, p<0.001). The prevalence of chronic heart failure was greater (26% vs. 13%, p<0.001), as was the incidence of renal failure (6.1% vs. 1.2%, p=0.003). A higher number of patients were classified within Killip classes 3-4 (24% vs. 2.6%, p<0.001). For patients with WBC above the median versus those below, there was a higher prevalence of chronic heart failure (24% vs. 16%, p=0.009). Killip 3-4 was also more common (22% vs. 4.2%, p<0.001). Patients with CRP and WBC at or above the median and an ‘intermediate-high’ ORBI score faced a higher risk of one-year mortality (HR CRP: 5.23, 95%CI: 2.59-10.6, p<0.001 and HR WBC: 6.15, 95%CI 3.04-12.4, p<0.001, figure 1). Conclusions An ‘intermediate-high’ ORBI risk score in STEMI patients was associated with significantly higher odds of increased levels of systemic inflammation within 0-96 hours of admission. An intermediate-high score combined with an elevated inflammatory response was associated with a five to six-fold increased risk of one-year mortality.Fig. 1:KM-plot, 1 year (scale is 1-0.9)