Short-and long-term individual variation in NT-proBNP levels in patients with stable coronary artery disease

Background: In addition to diagnosis of heart failure (HF) natriuretic peptides (BNP and NT-proBNP) may be used for risk prediction in stable and acute coronary artery disease. The aim of the study was to evaluate the short- and long-term individual variation of NT-proBNP in patients with stable coronary artery disease. Methods: Twenty-four patients with suspected stable coronary artery disease and scheduled for elective coronary angiography were included. Blood samples were drawn at enrolment and, on average 3 weeks later, serially the day prior to coronary angiography. NT-proBNP was determined using Elecsys proBNP sandwich immunoassay (Roche Diagnostics). Results: The individual variation in NT-proBNP over 4 h was 11.8%, over 20 h 12.4% and over 3 weeks 20.4%. The corresponding positive and negative lognormal reference change values (RCV) were +41/-29%, +42/-30% and + 76/-43%, respectively. No significant circadian variation was found. Conclusions: Our results suggest that an increase in NT-proBNP levels of >42% or a decrease of >30% is needed to indicate a reliable short-term change; and for a long-term change an increase of >76% or a decrease of >43% is required. This should be considered when interpreting changes in NT-proBNP levels. (C) 2013 Elsevier B.V. All rights reserved.