Interleukin-6 as a predictor of cardiovascular events in patients with non-ST elevation acute coronary syndrome and troponin-negative

AimRisk stratification in acute coronary syndrome without ST-segment elevation (NSTE-ACS) and troponin-negative remains a challenge. We evaluated the value of interleukin-6 (IL-6) and amino-terminal pro-B-type natriuretic peptide (NT-proBNP) in the prognosis assessment of low-moderate risk NSTE-ACS and troponin-negative, and whether these biomarkers could improve the predictive performance of the established thrombolysis in myocardial infarction (TIMI) risk score.MethodsA total of 212 low-moderate risk patients with NSTE-ACS and troponin-negative were prospectively studied. Clinical follow up at 6months was performed for adverse endpoints.ResultsA total of 28 patients (13.5%) presented adverse clinical events. Those with adverse clinical events were associated with higher levels of IL-6 [8.58 (5.13-20.95)ng/l vs. 6.12 (4.16-9.14)ng/l, p=0.043] and NT-proBNP [275.3 (108.6-548.2)ng/l vs. 126.8 (55.97-430.20)ng/l, p=0.046]. In moderate risk group, we observed a higher event rate in patients with troponin-negative but elevated levels of IL-6 (p=0.024). Only elevated IL-6 (>12.40ng/l) was an independent predictor of adverse outcomes [hazard ratios: 3.62, 95% confidence interval (CI) 1.69-7.75, p=0.001]. The addition of IL-6 and history of ischaemic heart disease (IHD) to TIMI risk score significantly improved both the discrimination (integrated discrimination improvement, p=0.003) and reclassification (Clinical Net reclassification improvement, p=0.010) of the model for adverse events.ConclusionsInterleukin-6 is an independent predictor of adverse events in low-moderate risk patients with NSTE-ACS and troponin-negative. Its use identifies a higher risk population in moderate-risk patients. This provides together with history of IHD a better discrimination and reclassification beyond that achieved with clinical risk variables from TIMI risk score in these patients.