The importance of cardiovascular system involvement in hyperthyroidism has
been recognized for many years. In the elderly patient, often with mild but
prolonged elevation of plasma thyroid hormones, symptoms and signs of hear
t failure and complicating atrial fibrillation (AF) may dominate the clinic
al picture and mask the more classic endocrine manifestations of the diseas
e. Impaired cardiopulmonary function and exercise capacity, significantly m
ore marked in older patients, is observed in hyperthyroidism. Thyrotoxicosi
s can aggravate pre-existing heart disease and can also lead to AF, congest
ive heart failure, or worsening of angina pectoris. Regarding the high inci
dence of AF in older patients with hyperthyroidism, it is also important to
detect subclinical hyperthyroidism in older patients with AF, thus warrant
ing the measurement of the serum thyrotropin (TSH) concentration for early
recognition and treatment. Most cardiac abnormalities return to normal once
a euthyroid state has been achieved, although AF may persist in a minority
. Optimal treatment requires rapid and definitive antithyroid therapy. Furt
hermore, anticoagulation is recommended for thyrotoxic patients with AF old
er than 50 years, those who have histories of previous emboli, hypertension
, or with echocardiographic evidence of left atrial enlargement and/or myxo
matous valves.