Ischaemic stroke, systemic embolism more likely in patients with hyperthyroidism-related AF

Patients with hyperthyroidism-related atrial fibrillation (AF) suffer from elevated risks of ischaemic stroke and systemic embolism (SSE), a new study has found.

Researchers conducted a retrospective, population-based cohort study, accessing the records of 615,724 oral anticoagulation-naïve patients with new-onset nonvalvular AF. Of these, 20,773 had hyperthyroidism-related AF. The primary outcome was the occurrence of ischaemic SSE compared between those with and without hyperthyroidism-related AF.

Over a median follow-up of 5.9 years, 1,806 episodes of SSE occurred in patients with hyperthyroidism-related AF, as opposed to 4,980 events in nonthyroidal counterparts. The corresponding incidence rates were 1.83 and 1.62 per 100 person-years.

The cumulative incidence rate of ischaemic SSE was significantly higher in patients with hyperthyroidism-related AF (p<0.001). The resulting risk estimate was likewise elevated in this group (vs nonthyroidal AF: hazard ratio [HR], 1.13, 95 percent confidence interval [CI], 1.07–1.19; p<0.001).

Time-dependent analysis showed that the higher risk of ischaemic SSE in patients with hyperthyroidism-related AF was significant only during the first year of AF diagnosis (HR, 1.36, 95 percent CI, 1.24–1.50; p<0.001). Beyond 1 year, the difference in hazards became comparable between groups.

“Hyperthyroidism-related AF patients have a high risk of stroke when initially diagnosed with AF and thus require regular follow-ups with appropriate anticoagulation strategy and prompt treatment for hyperthyroidism,” the researchers said.