Association between N-terminal pro-BNP and 12 months major adverse cardiac events among patients admitted with NSTEMI

Background: In recent years, the hospital admission rate of non-ST-elevation myocardial infarction (NSTEMI) patients has exhibited an increasing trend, and a forthcoming transition from ST- elevation myocardial infarction (STEMI) to NSTEMI has been observed in China. The association between serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) and major adverse cardiac events (MACEs) within 12 months after discharge among patients with NSTEMI remains unclear. Methods: A total of 1,357 consecutively admitted NSTEMI patients were from the TAMI cohort. The patients' baseline demographic and clinical information were collected, and follow-up was carried out for 12 months. The primary outcome was composite MACEs consisting of all-cause death, hospital admission for unstable angina, hospital admission for heart failure, non fatal recurrent myocardial infarction, and target lesion revascularization (TLR). We adopted a Cox proportional hazard model to analyze the effect of NTproBNP on MACEs and quantified the added prognostic value of NT-proBNP on the Global Registry of Acute CoronaryEvents (GRACE) risk score using the Harrell C-index, NRI, and IDI. Results: The overall average follow-up period was 313 days. In total, 211 (15.55%) patients suffered from at least one MACE, and 97 patients were lost to follow-up, with a median follow-up time of 147 days. As the NT-proBNP level increased, a significant uptrend in the incidence of composite MACEs, all-cause death, and heart failure was observed. The multivariable Cox model revealed that NT-proBNP was an independent risk factor for composite MACEs [medium- vs. low-, HR: 2.19 (1.45-3.32), P=0.0002]; [highvs. low-, HR: 3.07 (1.78-5.29), P<0.0001], as well as for all-cause death and heart failure. Subgroup analysis indicated that NT-proBNP was a robust prognostic biomarker, and the prognostic value was more evident for patients older than 60 years and whose LVEF was less than 40%. NT-proBNP (log-scale) was moderately correlated with the GRACE score (r=0.58, P<0.0001). The Harrell C-index of NT-proBNP combined with the GRACE score was 0.7715, which was higher than that of the GRACE score alone (0.7149) for predicting composite MACEs, and this improvement was verified by significant IDI (0.064, 95% CI: 0.027-0.106). Conclusions: NT-proBNP is a robust long-term prognostic biomarker for patients diagnosed with NSTEMI, especially for older patients and those with impaired cardiac ejection function. Combined usage of NT-proBNP levels with the GRACE score might help identify a subset of NSTEMI patients at a particularly high risk of MACEs 12 months after discharge.