Increased Levels of Cardiac Troponin I in Subjects with Extremely Low B-type Natriuretic Peptide Levels

Satoshi Sugawa,Michihiro Yoshimura,Kiminori Kato,Izuru Masuda

doi:10.1038/s41598-018-23441-z

Abstract

Because of the lack of studies focused on the biological implications of extremely low B-type natriuretic peptide (BNP) levels, we investigated whether extremely low BNP levels could be harmful to the cardiovascular system due to compromised cardio-protection. By using cardiac troponin I (cTnI) as an indicator of cardiovascular disorder, we assessed whether cTnI was inversely associated with BNP in populations with low BNP levels. A total of 2,001 apparently healthy subjects older than 38 years were included in this study. We defined subgroups from this population by limiting the maximum BNP level with cut-off values ranging from 1 through 20 pg/mL and performed covariance structure analyses by comparing log(BNP) with log(cTnI) in each subgroup. The beta values between log(BNP) and log(cTnI) sharply decreased as the BNP cut-off was reduced from 20 pg/mL (beta = 0.04) to 1 pg/mL (beta = −0.29) and became significant when the BNP cut-off levels were lower than 4 pg/mL (p < 0.005). In subgroups with BNP levels lower than 4 pg/mL, elevation in cTnI level was inversely associated with BNP (p < 0.005), which suggests that insufficient BNP may play a pathogenic role in the occurrence of cardiovascular abnormalities.

Highlights

Cardiac troponin I is expressed in the myocardium as a cardio-specific isoform, and it is ideally suited as a marker of myocardial damage[8]
In a 10-year follow-up of the Inter[99] study, Hansen et al showed with a cohort of 6,238 general population that metabolically healthy obese subjects had a higher risk of ischaemic heart disease (IHD) than metabolically healthy subjects with normal weight[12]
Because of the cardio-protective effects exerted by B-type natriuretic peptide (BNP), we hypothesized that the increased risk of IHD in individuals with obesity is due to well-known risk factors and to the compromised cardio-protection of the reduced BNP level

Summary

Introduction

Cardiac troponin I (cTnI) is expressed in the myocardium as a cardio-specific isoform, and it is ideally suited as a marker of myocardial damage[8]. By a covariance structure analysis in 1,252 patients with cardiac disorders, we confirmed that low BNP level, as well as hypertension, dyslipidaemia and haemoglobin A1c (HbA1c), but not body mass index (BMI) was significantly associated with the incidence of IHD (p < 0.001)[16]. To confirm this hypothesis further, by using cTnI as an indicator of cardiac disorders in this study, we assessed whether low BNP level was associated with an enhanced cardiovascular risk in the general population

Methods

Results

Conclusion