Evaluation of left atrium phasic functions, mechanics andthe correlation with atrial fibrilation in subclinic hypothyroid patients

Objective: Subclinical hypothyroidism is a common disease in Cardiology outpatient clinics. In the previous studies, subclinical hypothyroidism was found to be associated with myocardial edema and fibrosis due to increased extracellular matrix components. Atrial fibrosis has an important role in the pathophysiology of atrial fibrillation. In the present study we aimed to investigate the correlation of PAF frequency with strain values, which is the indicator of atrial fibrosis, in patients with subclinical hypothyroidism. Material and Method: In our study, we included 42 subclinical hypothyroid and 43 euthyroid, a total of 85 patients in our clinic with CAD, HT, HL. In addition to conventional echocardiographic measurements, the relationship between tissue Doppler echocardiography and 2D speckle tracking strain echocardiography, left ventricular functions, volumetric left atrium functions, left peak longitudinal and contractional strain values, left atrial functions and development of paroxysmal atrial fibrillation were evaluated in these patients. Results: In patients with subclinical hypothyroidism, left atrium volume, diameters and LAVI were higher (p <0.05). E/A ratio was significantly lower than the control group (p <0.05). There was no significant difference between other diastolic parameters (p> 0.05). Left ventricle GLS was lower than the control group (p <0.05). There was no difference between left ventricular systolic function, diameters and left atrial emptying fractions (p> 0.05). The mean PALS, PACS, (p <0.001) systolic strain rate and early diastolic strain rate variables were different in two groups (p <0.05). The mean age of the PAF group was higher than the control group (p <0.001), left atrium diameters and LAVI were higher (p <0.05). PALS and PACS values obtained from the two chambers were significantly lower in the PAF group (p <0.01). As a result of the regression analysis, it was determined that age was an independent determinant in showing the presence of PAF. PALS showed negative correlation with age, left atrium volume, LAVI (p <0.001), E/e ' ratio (p <0.01) and LDL values (p <0.05). The peak atrial longitudinal strain measured from two chambers below 20.5 showed the presence of PAF with 31% sensitivity and 94% specificity. Conclusion: In subclinical hypothyroidism, the left ventricular GLS, left atrium PALS and PACS values were lower than the control group without any change in left ventricular EF and left atrial discharge fractions. The decrease in left atrial strain parameters may predict the remodeling and the development of AF. Larger studies are needed to reveal this relationship.