The value of N-terminal fragment of brain natriuretic peptide and tissue inhibitor of metalloproteinase-1 levels as predictors of cardiovascular outcome in the LIPID study

Abstract

Aims: We sought to determine the association between two major biomarkers, the inactive N-terminal fragment of brain natriuretic peptide (NT-proBNP) and tissue inhibitor of metalloproteinase-1 (TIMP-1) and long-term cardiovascular outcomes in a cohort of subjects who had a myocardial infarction or unstable angina 3-36 months previously. Methods and results: Plasma NT-proBNP and TIMP-1 were measured in a nested case control study of 250 randomly matched subject pairs enrolled in the long-term intervention with pravastatin in ischaemic disease (LIPID) and LIPID extended follow-up studies. Cases (n = 250) were defined as those who had a cardiovascular death, non-fatal myocardial infarction or stroke during the studies. Controls (n = 250) remained event-free for the same follow-up duration (average 2.5 years) as the matched cases. The relationships between cases and plasma NT-proBNP and TIMP-1 were adjusted for the LIPID risk score, treatment allocation and other biomarkers (CRP, IL-6 and white cell count), and examined using a multivariable conditional logistic regression model. NT-proBNP levels were significantly higher in the cases than in the controls [389 (152-864) vs. 198 (93-416) pg/mL, median (25%-75% percentiles), P < 0.001]. The odds ratio (OR) of recurrent cardiovascular events in individuals in the highest quartile was three times higher than those in the lowest quartile (95% confidence interval (CI) 1.8-5.1; P < 0.001). Similarly, TIMP-1 levels were significantly higher among cases compared with controls (806 vs. 736 pg/mL, median: highest vs. lowest quartile: OR 2.8, 95% CI 1.6-4.7; P < 0.001). After adjustment for the LIPID risk score, treatment with pravastatin and other biomarkers, both NT-proBNP and TIMP-1 predicted cardiovascular events significantly and independently of each other. Conclusion: The study suggests that in subjects with stable ischaemic disease, NT-proBNP and TIMP-1 are independent predictive markers of coronary heart disease outcome.