Elevated Arterial Stiffness and Diastolic Dysfunction in Subclinical Hypothyroidism

Background: Thyroid hormone is associated with arterial stiffness and left ventricular diastolic function in hypothyroid disease. The relationship of thyroid hormone level to cardio-ankle vascular index (CAVI) and left ventricular diastolic function, however, remains unclear in subjects with subclinical hypothyroidism. Methods and Results: We conducted a cross-sectional study of 83 patients with untreated subclinical hypothyroidism and compared them with 83 randomly selected controls from health check-ups. Log N-terminal prohormone of brain natriuretic peptide (NT-proBNP), C-reactive protein (CRP), and arterial stiffness were measured. In addition, we measured early diastolic mitral annular velocity (E') in 43 participants with subclinical hypothyroidism and in 40 controls. When compared with the control group, patients with subclinical hypothyroidism had higher logNT-proBNP (1.9 +/- 0.5 vs. 1.7 +/- 0.3 pg/ml, P<0.05), CRP (0.22 +/- 0.04 vs. 0.09 +/- 0.06 mg/dl, P<0.05), and CAVI (8.8 +/- 1.7 vs. 7.8 +/- 1.4, P<0.001) and lower E' (5.8 +/- 1.7 vs. 7.5 +/- 2.1 cm/s, P<0.001). CAVI was significantly associated with logNT-proBNP, CRP and E' in the subclinical hypothyroidism group. Conclusions: High logNT-proBNP was associated with a raised CAVI in patients with subclinical hypothyroidism. Subclinical hypothyroidism may be a risk factor for cardiovascular events related to arterial stiffening and left ventricular diastolic dysfunction.