Amino-terminal pro-B-type natriuretic peptide (NT-proBNP) levels 3 months after myocardial infarction are more strongly associated with magnetic resonance-determined ejection fraction than NTproBNP levels in the acute phase.

Background: The relationship between levels of amino-terminal pro-B-type natriuretic peptide (NT-proBNP) and left ventricular function determined by magnetic resonance imaging (MRI) in ST-segment-elevation myocardial infarction (STEMI) is largely unknown.

Methods And Results: This was a substudy of the Norwegian Study on District Treatment of STEMI, in which patients received thrombolysis followed by early or late invasive strategy. NT-proBNP was measured at 3 days and 3 months after the myocardial infarction, and magnetic resonance imaging was performed after 3 months (n = 160). Log NT-proBNP levels at both time points were significantly associated with ejection fraction (EF) (r(2) values 0.25 and 0.42, respectively) as well as infarct size (r(2) values 0.38 and 0.47, respectively; P < .0001 for all, adjusted for confounders). Furthermore, receiver operating characteristic (ROC) curves used to analyze the ability of NT-proBNP to discriminate long-term low EF (≤40%) and large infarct size (≥15.7%), were significant at both time points (P < .001 for all). Pairwise comparison of the ROC curves showed a significantly better performance of NT-proBNP at 3 months compared with 3 days for discrimination of low EF (P = .023).

Conclusion: Repeated measurements of NT-proBNP in STEMI patients showed that NT-proBNP levels at 3 months were more strongly associated with long-term EF and infarct size than NT-pro BNP levels after 3 days. Our data suggest that measurement of NT-proBNP 3 months after myocardial infarction is a better indicator of left ventricular function compared with NT-proBNP in the acute phase.