Usefulness of NT-proBNP in the Follow-Up of Patients after Myocardial Infarction

Abstract

Background: Since serial analyses of NT-proBNP in patients with acute coronary syndromes have shown that levels measured during a chronic, later phase are a better predictor of prognosis and indicator of left ventricular function than the levels measured during an acute phase, we sought to assess the association of NT-proBNP, measured 6 months after acute myocardial infarction (AMI), with traditional risk factors, characteristics of in-hospital and early postinfarction course, as well as its prognostic value and optimal cut-points in the ensuing 1-year follow-up. Methods: Fasting venous blood samples were drawn from 100 ambulatory patients and NT-proBNP concentrations in lithium-heparin plasma were determined using a one-step enzyme immunoassay based on the «sandwich» principle on a Dimension RxL clinical chemistry system (DADE Behring-Siemens). Patients were followed-up for the next 1 year, for the occurrence of new cardiac events. Results: Median (IQR) level of NT-proBNP was 521 (335-1095) pg/mL. Highest values were mostly associated with cardiac events during the first 6 months after AMI. Negative association with reperfusion therapy for index infarction confirmed its long-term beneficial effect. In the next one-year follow-up of stable patients, multivariate Cox regression analysis revealed the independent prognostic value of NT-proBNP for new-onset heart failure prediction (p=0.014), as well as for new coronary events prediction (p=0.035). Calculation of the AUCs revealed the optimal NT-proBNP cut-points of 800 pg/mL and 516 pg/mL, respectively. Conclusions: NT-proBNP values 6 months after AMI are mainly associated with the characteristics of early infarction and postinfarction course and can predict new cardiac events in the next one-year follow-up.