Prevalence and mortality of cardiovascular events in patients with hyperthyroidism: a nationwide cohort study in the United States

Background: Little is known about the implications of hyperthyroidism on cardiovascular diseases like myocardial infarctions (MI), ischemic strokes, and hemorrhagic strokes. Previous studies implicate hyperthyroidism as a risk factor for MI and ischemic stroke. Cardiovascular disease is the leading cause of death in the US, and the possibility of hyperthyroidism contributing to this disease burden warrants investigation in a US patient population. Methods: The National Readmission Database (NRD) from 2010 to 2017 was used to identify adults who had a new-onset diagnosis of MI, ischemic stroke, or hemorrhagic stroke. Risk factors for mortality, prolonged hospital stay, and hospital cost were analyzed with binary logistic regression. Results: A total of 278,609,748 hospital records were reviewed. Of these, 15,685,461 were hospitalized for adverse cardiovascular events with concomitant hyperthyroidism, roughly 4.5 per 1,000 cases. Patients with MI and hemorrhagic stroke with thyrotoxicosis had a lower mortality rate than euthyroid patients (OR 0.81, 95% CI: 0.78-0.84, P<0.001 and OR 0.72, 95% CI: 0.67-0.77, P<0.001, respectively). Thyrotoxicosis was associated with increased hospital stay (MI: OR 1.35, 95% CI: 1.32-1.38, P<0.001; ischemic: OR 1.38, 95% CI: 1.35-1.41, P<0.001; hemorrhagic: OR 1.33, 95% CI: 1.25-1.40, P<0.001), expenditures in ischemic (OR 1.31, 95% CI: 1.28-1.34, P<0.001) and hemorrhagic stroke patients (OR 1.18, 95% CI: 1.12-1.24, P<0.001). Conclusions: Patients that experienced MI or hemorrhagic stroke with concomitant thyrotoxicosis were observed to have a lower mortality rate than euthyroid patients but had with an increased length of hospital stay. Patients who had ischemic or hemorrhagic stroke with thyrotoxicosis had a significantly higher hospital cost. The hyperdynamic state underlying hyperthyroidism may be protective in these adverse events. Further studies into these physiological changes are warranted.