Endocrine Abstracts

Background and aim: Atrial fibrillation (AF) is a relatively common complication of thyrotoxicosis. The aim of this study was to estimate the association between echocardiographic variables and AF in patients with Graves’ disease.

Patients and methods: Standard echocardiographic examination was performed in 166 patients with Graves’ disease (40 men and 126 women, mean age±S.D. 43.9±12.8 years) referred to the endocrinological department. 81 of them had paroxysmal (35) or chronic (46) AF due to thyrotoxicosis. Patients with concomitant heart diseases were not included in the study. 18 patients with chronic AF spontaneously reverted to sinus rhythm after they became euthyroid and remained in sinus rhythm during the follow-up (not less than 12 months).

Results: Mean maximal left atrial diameter (LAD) was significantly higher in patients with chronic AF than in patients with sinus rhythm (4.40±0.63 cm vs 3.37±0.53 cm correspondingly, Mann-Whitney U=615.5; P<0.001). The presence of chronic AF significantly correlated with LAD after controlling for age and sex (partial correlation coefficient 0.539; P<0.001). No significant correlation was found between the echocardiographic variables and the presence of paroxysmal AF (P>0.05).

In multiple regression analysis LAD was the best echocardiographic predictor of the restoration of sinus rhythm in patients with chronic AF after they became euthyroid (R²=0.460; P=0.002). Discriminant analysis allowed to classify patients with chronic AF into 2 groups – those who reverted to sinus rhythm after achieving euthyroidism (LAD <4.31 cm) and those who did not (LAD >4.31 cm) with the probability of correct classification 82.6%.

Conclusion: Echocardiographic LAD can be used for the prognosis of the spontaneous reversion to sinus rhythm in patients with chronic AF related to thyrotoxicosis after achieving euthyroid state.