A higher incidence of cardiovascular complications in hyperthyroid patients with Graves’ disease in comparison to hyperthyroid patients with subacute thyroiditis

Background: Hyperthyroidism, as well as systemic inflammation, are associated with a higher incidence and complications of cardiovascular disease. Both in Graves’ disease and subacute thyroiditis, patients are hyperthyroid. However, in Graves’ disease, there is an autoimmune process in the thyroid, and in subacute thyroiditis, hyperthyroidism is accompanied by systemic inflammation. It is not known if the rate of cardiovascular complications is higher in the course of Graves’ disease or subacute thyroiditis.. Methods: We performed a retrospective study of all hyperthyroid patients newly diagnosed with Graves’ disease or subacute thyroiditis between January 1st 2018 and December 31st 2021 at the Department of Nuclear Medicine, University Medical Centre Ljubljana. Cardiovascular complications in the period 3 months before or after diagnosis were registered. Values are expressed as mean (SD).. Results: The sample analysis included 1028 patients (247 with subacute thyroiditis, 781 with Graves’ disease). The two groups did not significantly differ by sex, age, and body mass index. A cardiovascular complication was registered in 78 patients; the incidence was significantly higher in Graves’ disease than in subacute thyroiditis (74 vs. 4, p<0.001). Compared to patients with subacute thyroiditis, patients with Graves’ disease had significantly lower TSH: 0.010 (0.006) vs. 0.024 (0.044) mIU/L (p<0.001), higher free T4: 44.1 (26.6) vs. 37.0 (14.7) pmol/L (p<0.001), higher incidence of diabetes: 4.3 vs. 0.4% (p=0.001), arterial hypertension: 12.2 vs. 5.7% (p=0.004) and smoking: 26.7 vs. 8.7% (p<0.001). In a logistic regression model, a significantly higher likelihood for cardiovascular complications was found in Graves’ disease vs. subacute thyroiditis (odds ratio 5.82, p=0.001), in patients with arterial hypertension (odds ratio 2.83, p=0.002), and in those with higher body mass index (odds ratio 0.92, p=0.043).. Conclusion: We report a higher incidence of cardiovascular complications in hyperthyroid patients with Graves’ disease in comparison to hyperthyroid patients with subacute thyroiditis. Patients with Graves’ disease were more severely hyperthyroid and had more adverse cardiovascular risk factors.