Acute cardiovascular events and all-cause mortality in patients with hyperthyroidism: a population-based cohort study

Objective: Several studies have shown an increased risk for cardiovascular disease (CVD) in hyperthyroidism, but most studies have been too small to address the effect of hyperthyroidism on individual cardiovascular endpoints. Our main aim was to assess the association among hyperthyroidism, acute cardiovascular events and mortality. Design: It is a nationwide population-based cohort study. Data were obtained from the Danish Civil Registration System and the Danish National Patient Registry, which covers all Danish hospitals. We compared the rate of all-cause mortality as well as venous thromboembolism (VTE), acute myocardial infarction (AMI), ischemic and non-ischemic stroke, arterial embolism, atrial fibrillation (AF) and percutaneous coronary intervention (PCI) in the two cohorts. Hazard ratios (HR) with 95% confidence intervals (95% CI) were estimated. Results: The study included 85 856 hyperthyroid patients and 847 057 matched population-based controls. Mean follow-up time was 9.2 years. The HR for mortality was highest in the first 3 months after diagnosis of hyperthyroidism: 4.62, 95% CI: 4.40-4.85, and remained elevated during long-term follow-up (> 3 years) (HR: 1.35, 95% CI: 1.33-1.37). The risk for all examined cardiovascular events was increased, with the highest risk in the first 3 months after hyperthyroidism diagnosis. The 3-month post-diagnosis risk was highest for atrial fibrillation (HR: 7.32, 95% CI: 6.58-8.14) and arterial embolism (HR: 6.08, 95% CI: 4.30-8.61), but the risks of VTE, AMI, ischemic and non-ischemic stroke and PCI were increased also 2-to 3-fold. Conclusions: We found an increased risk for all-cause mortality and acute cardiovascular events in patients with hyperthyroidism.