Abstract 2518: Impact of Hypothyroidism on Outcomes of Atrial Fibrillation Treatment Strategies
Background: Hypothyroidism may coexist with atrial fibrillation (AF) or be due to amiodarone therapy in AF. Its impact on mortality & hospitalization events is unknown.
Methods: We compared a composite mortality & hospitalization endpoint for assessment of outcomes in AF pts who were randomized to either amiodarone or a rate control strategy (Rate) in the AFFIRM trial. They were stratified by the presence or absence of thyroid disease requiring replacement thyroid hormone therapy, Cardiovascular (CV) hospitalizations were analyzed for prespecified or observed intercurrent clinical events.
Results: 735 pts randomized to primary amiodarone therapy (Amio) were compared to 2027 pts randomized to Rate. 56 pts (7.6%) with Amio & 178 pts (8.8%) with Rate had thyroid abnormalities identified (p=.33). Increasing age & female gender were more common in thyroid disease pts regardless of randomized therapy (p<.0001 for both). Pacemaker therapy & diabetes were more common in pts with thyroid disease with Amio (p=.05 for both) but not with Rate. Thyroid disease as defined had no impact on mortality in either group. However, there was a significant increase in CV hospitalization events with thyroid disease in Amio pts (figure⇓, p<.001). Cox hazard analysis adjusting for age, gender, pacemaker therapy & diabetes maintained Amio related risk (Hazard ratio 2.072, p<.0001). Persistent AF & cardioversion were more often seen during CV hospitalizations with Amio ( p <.05)
Thyroid abnormalities were more common in elderly & female AF pts in AFFIRM.
Thyroid disease can adversely impact CV outcomes in pts treated with Amio despite replacement thyroid hormone therapy.