Rationale: Evaluation of the cardiovascular system in patients with common thyroid disorders could be of interest from the perspective to identify new risk factors for cardiovascular events. Whether cardiovascular abnormalities associated with thyrotoxicosis would be reversible after its treatment, needs elucidation.

Aim: To assess the degree of restoration and prerequisites for reversion of the signs and symptoms of cardiac injury in the long term after conservative and surgical cure of thyrotoxicosis in patients with diffuse toxic goiter (DTG).

Materials and methods: This was an open longitudinal retrospective study performed in the Regional Center for Endocrine Surgery, Chelyabinsk Municipal Clinical Hospital No.  1 in 124 patients with past history of DTG. By the time of examination, all patients were in a stable clinical and laboratory remission after the withdrawal thyrostatic agents or were in controlled post-operative hypothyroidism for 1.5 to 5  years after surgery for DTG. The mean age of the conservatively treated patients (n=62) was 39.9±1.31 years (19 to 55  years). The mean age of the patients that had been treated surgically (n=62; subtotal thyroid resection) was 41.1±1.4 years (21 to 56 years). We compared with patients' complaints, electrocardiographic and echocardiographic parameters by the time of examination with the corresponding data at the time of the primary referral.

Results: In the long term after the elimination of thyrotoxicosis, 56.5%  (35/62) of the patients who had underwent surgery, were complaining of dyspnea, 54.8%  (34/62) of palpitations, and 50%  (31/62) of cardialgias (p<0.01), whereas among the conservatively treated patients the corresponding complaints were present in 59.7%  (37/62), 64.5%  (40/62), and 56.5%  (35/62) (p<0.01). Ninety nine (99) percent of the patients, who had arterial hypertension before the treatment, remained hypertensive at the follow-up. In 30% of the surgically treated patients the severity of arterial hypertension was higher than initially. In the surgery group, there was a decrease in the left atrium diameter in 17 patients and in the end-diastolic diameter of the right ventricle in 24 patients; all these patients did not have hypertension at baseline. No restoration of the heart chamber diameters was seen after conservative treatment and after surgery in patients with arterial hypertension. ST segment and T wave abnormalities were not associated with any clinical symptoms both at baseline and in the long term. At the long term follow up all patients had normal thyroid-stimulating hormone (TSH) and thyroxine (T4) levels, with no associations between TSH and T4 levels and clinical and instrumental assessment results. All patients with past history of DTG continued to have tachycardia, arterial hypertension, diastolic dysfunction and increased left ventricular myocardial mass.

Conclusion: Cardiovascular abnormalities persisted for a  long time after the elimination of DTG. Arterial hypertension that had arisen against the background of DTG had a negative impact on the structural and functional state of the heart in this disease, irrespective of the treatment method used. In the patients with past history of DTG, we identified such predictors of heart failure as tachycardia, arterial hypertension, diastolic dysfunction, increased left ventricular myocardial mass.