Anticoagulation and Atrial Fibrillation in the Bradycardia- Tachycardia Syndrome

JF, an 80-year-old woman, presented to the New England Medical Center with syncope. She had a ten-year history of edema due to mild congestive heart failure, treated with a thiazide diuretic and digoxin. Extensive evaluation revealed paroxysmal atrial fibrillation and sinus bradycardia; a diagnosis of sick sinus or bradycardia-tachycardia syndrome was made. Syncope did not recur and pacemaker therapy was not considered. Anticoagulation was begun as prophylaxis against systemic embolization. JF returned to the hospital one month later with microscopic hematuria. Her renal function was normal, and intravenous pyelography showed no abnormality. Urinary bleeding subsided spontaneously, but anticoagulants were discontinued. A consultation was requested from the Division of Clinical Decision Making to clarify the risks and benefits of prophylactic anticoagulation in atrial fibrillation associated with the bradycardiatachycardia syndrome.