Abstract
BackgroundAltered thyroid function and increased rates of N-terminal pro-B-Type natriuretic peptide (NT-pro-BNP) are highly prevalent in coronary artery disease (CAD) patients with heart failure, and are associated with unfavorable prognosis. This study was undertaken to examine the relationship and prognostic impact of thyroid hormones, inflammatory biomarkers, and NT-pro-BNP on long-term outcomes in patients after acute coronary syndrome (ACS).MethodsThe study comprised of 642 patients (age 58 ± 10 years, 77 % male) attending an in-patient cardiac rehabilitation program after experiencing ACS. Patients were evaluated for demographic, clinical and CAD risk factors as well as thyroid hormones (e.g., fT3, fT4 level, fT3/fT4 ratio), inflammatory biomarkers (hs-CRP, IL-6) and NT-pro-BNP levels. Data on fT3/fT4 ratio and NT-pro-BNP levels were not normally distributed and were natural-log transformed (ln). Both all-cause (cumulative) and cardiac-related mortality were considered the primary outcomes of interest.ResultsAccording to the Cox model, age, NYHA class, (ln)NT-pro-BNP levels (HR 1.53, 95 % CI 1.13–2.07), fT4 level (HR 1.15, 95 % CI 1.04–1.27), and (ln)fT3/fT4 ratio (HR 0.08, 95 % CI 0.02–0.32) were the most important predictors of all-cause mortality among CAD patients after ACS. Similarly, age, NYHA class, (ln)NT-pro-BNP levels (HR 1.62, 95 % CI 1.11–2.36), fT4 (HR 1.15, 95 % CI 1.02–1.29) and (ln)fT3/fT4 ratio (HR 0.10, 95 % CI 0.02–0.55) independently predicted cardiac-related mortality. Kaplan-Meier analyses provided significant prognostic information with the highest risk for all-cause mortality in the low cut off measures of fT3/fT4 ratio <0.206 and NT-pro-BNP ≥290.4 ng/L (HR 2.03, 95 % CI 1.39–2.96) and fT4 level >12.54 pg/ml (HR = 2.34, 95 % CI 1.05–5.18). There was no association between hs-CRP, IL-6 and mortality in CAD patients after ACS.ConclusionsThyroid hormones (i.e., fT4 level and fT3/fT4 ratio) together with NT-pro-BNP level may be valuable and simple predictors of long-term outcomes of CAD patients after experiencing ACS.
Highlights
Altered thyroid function and increased rates of N-terminal pro-B-Type natriuretic peptide (NT-pro-BNP) are highly prevalent in coronary artery disease (CAD) patients with heart failure, and are associated with unfavorable prognosis
When we stratified participants into two groups according to cut-off values, we found that higher free total thyroxine (T4) (fT4) levels were associated with worse outcomes (HR 2.34, 95 % confidence interval (CI) 1.05–5.18, p = 0.036) (Fig. 2c)
Our study revealed that age, New York Heart Association (NYHA) class,NTpro-BNP, fT4 andfT3/fT4 ratio were independent predictors of all-cause mortality and that NYHA class,NT-pro-BNP, fT4,free total triiodothyronine (T3) (fT3)/fT4 ratio remained independent predictors of cardiac-related mortality
Summary
Altered thyroid function and increased rates of N-terminal pro-B-Type natriuretic peptide (NT-pro-BNP) are highly prevalent in coronary artery disease (CAD) patients with heart failure, and are associated with unfavorable prognosis. Altered thyroid function in the absence of primary thyroid disease is characterized by low total triiodothyronine (T3), free T3 (fT3) levels with normal total thyroxine (T4) and thyroid-stimulating hormone (TSH) This is due to reduced enzyme 5′ monodeiodinase activity, responsible for converting T4 into T3 in the peripheral tissues [12, 13]. In contrast others have suggested that hypothyroidism alters NT-pro-BNP concentrations [20, 21]
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