THE IMPACT OF THYROID HORMONE REPLACEMENT THERAPY ON LEFT VENTRICULAR DIASTOLIC FUNCTION IN PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM

Subclinical hypothyroidism is associated with a moderately increased risk of developing events associated with heart failure and an increased risk of cardiovascular mortality among older persons with a TSH level within 7-10 honey/L. the Aim of our prospective study was to evaluate the effect of hormone replacement therapy with low doses of L-thyroxine (6.25-25 mg/day) on diastolic left ventricular function in patients with concomitant subclinical hypothyroidism. The study involved 33 patients (F/M: 24/9, the average age 51,21 ± 4,32 years) with subclinical hypothyroidism and 25 healthy volunteers (F/M: 17/8, the average age 49,33 ± 3,67 years). All patients and control group was performed by standard echocardiography and Doppler. Among the standard indexes, special attention was focused on the ratio E/a (ratio of maximal velocities of ventricular filling in early-E and late-A phases) and the determination of the thickness of the intraventricular septum. All patients with subclinical hypothyroidism had received hormone replacement therapy with thyroxine (average dose 19,35 ± 3.67 mg/day) for 6 months in order to achieve a euthyroid state. Original, patients with subclinical hypothyroidism showed significantly lower E (0,79 ± 0,22 against 0,93 ± 0,19, p <0.001), E/A ratio (1,19 ± 0,29 against 1,31 ± 0,25, p <0.003) and a higher thickness of interventricularseptum (0,99 ± 0,14 against 0,89 ± 0,18, p <0.001). After 6 months of hormone replacement therapy with thyroxine patients with subclinical hypothyroidism showed a significantly higher ratio of E/A (1,28 ± 0,21 against 1,19 ± 0,29, p <0.001) and a decrease in the thickness of the intraventricular septum (0,92 ± 0,16 against 0,99 ± 0,14, p <0.001). Hormone replacement therapy with low doses of Lthyroxine can improve diastolic left ventricular function in patients with subclinical hypothyroidism. In patients with cardiovascular risk factors and in the elderly it is necessary to closely monitor the occurrence of symptoms of iatrogenic hyperthyroidism during titration of the dose of thyroxine.