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Summary

Aim

Risk 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.

Methods

A total of 212 low–moderate risk patients with NSTE-ACS and troponin-negative were prospectively studied. Clinical follow up at 6 months was performed for adverse endpoints.

Results

A 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 (> 12.40 ng/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.

Conclusions

Interleukin-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.