Effects of Hyperthyroidism on Coronary Artery Disease: A Computed Tomography Angiography Study

Background: Changes in thyroid hormone concentration can negatively affect the cardiovascular system. Subclinical hyperthyroidism has been linked to an increase of cardiovascular heart disease, however, clinical effects and significance are still uncertain. Therefore, we analyzed coronary computed tomography angiographies of patients with overt and subclinical hyperthyroidism for quantitative parameters and plaque morphology. Methods: Seven hundred forty-four (47.1% female) patients who underwent coronary computed tomography angiography were stratified into 3 groups: 51 patients with overt, 74 patients with subclinical hyperthyroidism, and 619 patients with euthyroidism. Analysis included grades of stenosis (no stenosis = 0, mild < 50%, intermediate 50%-70%, or high-grade > 70%) and plaque types (noncalcified, mixed, and calcified), segment involvement score (SIS), noncalcified SIS, and high-risk plaque features (napkin ring sign, low attenuation plaque, spotty calcifications, positive remodelling). Results: Patients with overt and subclinical hyperthyroidism had more high-grade stenoses (39.2% vs 37.8% vs 24.2%; P = 0.007) and a higher coronary calcium score (456.5 vs 199.5 vs 155.9; P < 0.0001). Also, a total higher plaque burden has been found (SIS: 3.3 vs 3.2 vs 2.2; P < 0.0001; noncalcified SIS (1.2 vs 1.1 vs 0.6; P < 0.0001)). Patients with overt hyperthyroidism, followed by those with subclinical hyperthyroidism, had the most high-risk plaque features: napkin ring (21.6% vs 9.5% vs 6.0%, P < 0.0001), low attenuation plaque (35.3% vs 27% vs 8.7%, P < 0.0001), spotty calcification (35.3% vs 18.9% vs 19.1%, P = 0.02), and positive remodelling (37.3% vs 37.8% vs 25.5%, P = 0.02). After a mean follow-up of 168 months, significantly more revascularizations were documented for hyperthyroid patients. Conclusions: Patients with subclinical and overt hyperthyroidism showed more high-grade coronary stenoses, plaque burden, and highrisk plaque features than patients with euthyroidism, which indicates that an increase of thyroid hormones might lead to coronary vascular degeneration and plaque instability.