Subclinical hypothyroidism and left ventricular mechanics: a three-dimensional speckle tracking study.

CONTEXT: Subclinical hypothyroidism (SHT) is associated with left ventricular (LV) remodeling. The LV mechanics has not been previously assessed by two- and three-dimensional (2DE and 3DE) speckle tracking imaging in the SHT patients.

OBJECTIVES: The objective of the study was to investigate LV mechanics by 2DE and 3DE speckle tracking in the SHT patients and evaluate the influence of levothyroxine therapy on LV remodeling.

DESIGN: We conducted a prospective study. All SHT patients received levothyroxine therapy and were followed up for 1 year after the euthyroid state had been achieved.

SETTING: The study was performed at a university hospital.

PATIENTS: We included 54 untreated women with SHT and 40 healthy control women who were of similar age.

MAIN OUTCOME MEASURES: The 2DE strain and strain rates, 3DE volumes, 3DE strain, and thyroid hormones levels were assessed.

RESULTS: The 2DE LV longitudinal and circumferential strain and systolic and early diastolic strain rates were significantly decreased in the SHT patients before therapy in comparison with the controls or the SHT patients after therapy. The 3DE LV cardiac output and ejection fraction were significantly reduced in the SHT patients at baseline compared with the controls or patients after 1 year of treatment. The 3DE LV longitudinal and radial strains were significantly lower in the SHT group before treatment in comparison with the controls or patients after therapy, whereas the 3DE LV circumferential and area strains gradually increased from untreated SHT patients, among the treated SHT patients, to the controls.

CONCLUSION: SHT significantly affects LV deformation assessed by 2DE and 3DE speckle tracking. The improvement of LV mechanics after 1 year of levothyroxine treatment is significant but incomplete.