An Assessment of Cardiac Risk Factors on Subclinical Hypothyroidism in Coronary Heart Disease Patients

Purpose: Subclinical hypothyroidism (SCH) is defined as a condition which shows an elevated serum thyroid-stimulating hormone (TSH) in the presence of normal free triiodothyronine (FT3) and tetraiodothyronine (FT4) levels. The effect of conventional factors for coronary heart disease (CHD) on the severity of SCH remains uncertain. Our aim was to evaluate the cardiac risk factors on various degrees of SCH in a cohort of CHD patients. Methods: CHD patients were retrospectively divided into euthyroid, mild and severe SCH groups according to their thyroid functional status. Heath data from patients, including present and past history, results of blood biochemistry and ultrasound echocardiography were analyzed using univariate and multivariate logistic regression. Results: Among the CHD patients with euthyroidism (N =118), mild SCH (N=70) and severe SCH (N=29), 5 of 13 related factors, including gender, smoking history, LVEF, E/A and antithyroid peroxidase autoantibody (anti-TPO) positive were significantly different among the three groups (p<0.05). Interestingly, according to the results of univariate logistic regression, patients without smoking history were more likely to have mild SCH (OR=0.125, p<0.001) and severe SCH (OR=0.187, p=0.009). Likewise, patients with low HDL-C level were more likely to have severe SCH (OR=0.401, p=0.030). However, according to the results of multivariate logistic regression, females were more inclined to have mild SCH than males (OR=6.380, p<0.001). And patients with anti-TPO positive were more likely to have severe SCH (OR=6.427, p=0.002). Conclusion: Female CHD patients and an anti-TPO positive result were 2 independent factors related to SCH.