Left ventricular end-diastolic strain rate recovered in hypothyroidism following levothyroxine replacement therapy: A strain rate imaging study.

BACKGROUND

This study aimed to explore the impact of overt hypothyroidism on diastolic left ventricular (LV) deformation and the effect of levothyroxine therapy using 2-dimensional speckle-tracking echocardiography (STE) strain rate (SR) imaging.

METHODS

Forty-seven newly diagnosed hypothyroidic patients and 51 controls were prospectively enrolled. All participants underwent comprehensive 2-dimensional echocardiography. Besides the recently recommended parameters of LV diastolic function, strain imaging for LV systolic global longitudinal strain (GLS), and diastolic SR imaging at isovolumic relaxation period (SRivr), early (SRe) and late (SRa) diastole were assessed. Repeated echocardiography in hypothyroidic patients was made 6 months after the euthyroidic state was achieved.

RESULTS

Hypothyroidic patients had a lower ejection fraction (EF) than the controls (68.6 ± 5.2% vs 71.5 ± 4.0%, P = 0.002) but all within normal range (57%-80% and 64%-79%, respectively). No difference in the ratio of early mitral flow (E) to early diastolic septal or lateral myocardial motion velocity (e') was found (both P > 0.05), but significant difference was identified for SRa (0.85 ± 0.17 [/s] vs 1.00 ± 0.17 [/s], P = 0.000) and GLS (-20.8 ± 3.2% vs -23.6 ± 2.3%, P = 0.000). Upon follow-up, LV SRa (1.01 ± 0.20 [/s], P = 0.99 vs control) normalized when GLS (-21.6 ± 3.1%, P = 0.004 vs control) remained worse than the controls.

CONCLUSION

This study demonstrates subtle LV diastolic impairment in untreated hypothyroidic patients using SR imaging, which normalizes with short-term therapy and predates GLS.