The effect of L-thyroxine treatment on ventricular dysfunction and pulmonary arterial stiffness in patients with subclinical hypothyroidism.

OBJECTIVE

In our study, we aimed at evaluating the change in biventricular functions and pulmonary arterial stiffness (PAS) in patients with subclinical hypothyroidism (SH) in whom euthyroidism was achieved with L-thyroxine therapy.

PATIENTS AND METHODS

70 SH patients and 75 healthy volunteers were included in our study consecutively. Baseline demographic and echocardiographic data of the participants were recorded. The data obtained in the control evaluation 6 months after the euthyroidism were achieved in the SH group patients started on L-thyroxine treatment and then compared with the baseline measurements.

RESULTS

The mean age of patients in the SH group was 44.1 ± 9.4 years and 47.1% were women. Euthyroidism in SH patients was achieved with a mean daily L-thyroxine treatment of 59 µg/day for a mean of 16.1 ± 4.5 weeks. Positive changes in metabolic and hormonal profiles were achieved after L-thyroxine treatment in SH patients. It was determined that left ventricular and right ventricular isovolumetric relaxation and myocardial performance index were higher in SH patients compared to the control group, and these measurements were observed to decrease significantly with L-thyroxine treatment (p < 0.05 for each). While PAS was 16.9 ± 3.1 kHz/ms in the control group, it was 25.2 ± 5.3 kHz/ms in the SH group (p < 0.05). After L-thyroxine treatment, PAS measurements decreased to 17.2 ± 3.2 kHz/ms (p < 0.05) in the SH group and showed a positive change. Thyroid-stimulating hormone (TSH) change (Δ TSH) with Δ E/A ratio (r: -0.407, p < 0.001), right ventricular myocardial performance index (Δ RV MPI) change (r: 0.404, p < 0.001) and PAS change (Δ PAS) (r: 0.458, p < 0.001) found to be correlated.

CONCLUSIONS

SH is associated with dysfunction in the biventricular and pulmonary vascular bed. Biventricular functions and PAS change positively in SH patients with L-thyroxine treatment.