Effect of cardiac resynchronization therapy on thyroid function.

BACKGROUND

Heart failure patients frequently have thyroid function abnormalities. Cardiac resynchronization therapy (CRT) is a major treatment for patients with advanced chronic heart failure. We aimed to investigate the effects of CRT on thyroid functions.

HYPOTHESIS: CRT improves thyroid functions.

METHODS

Fifty-seven patients (42 male, 15 female; mean age 58 ± 13 y) undergoing CRT were included in the study. Serum levels of thyroid hormones and echocardiographic parameters were measured before and 6 months after CRT. A response to CRT was defined as a reverse remodeling detected by a relative increase of ≥15% in left ventricular ejection fraction.

RESULTS

The clinical status and functional capacity of the patients in the remodeling group were improved significantly. The mean New York Heart Association class was reduced from 3.2 ± 0.4 to 2.2 ± 0.4 (P<0.001). The free triiodothyronine (fT3) level increased from 2.67 pg/mL to 2.97 pg/mL in the reverse remodeling group (P = 0.005). The fT3/fT4 ratio increased from 1.81 to 2.34 (P = 0.006).

CONCLUSIONS

CRT improves fT3 levels and fT3/fT4 ratio, which may play an important role in reverse remodeling.