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.