TRIIODOTHYRONINE THERAPY LOWERS THE INCIDENCE OF ATRIAL-FIBRILLATION AFTER CARDIAC OPERATIONS

Background. Cardiopulmonary bypass results in a euthyroid sick state, and recent evidence suggests that perioperative triiodothyronine (T3) supplementation may have hemodynamic benefits. In light of the known e ffects of thyroid hormone on atrial electrophysiology, we investigated the effects of perioperative T3 supplementation on the incidence of p ostoperative arrhythmias. Methods. One hundred forty-two patients with depressed left ventricular function (ejection fraction < 0.40) underg oing coronary artery bypass grafting were randomized to either T3 or p lacebo treatment groups in a prospective, double-blind fashion. Triiod othyronine was administered as a 0.8 mu g/kg intravenous bolus at the time of aortic cross-clamp removal followed by an infusion of 0.113 mu g . kg(-1). h(-1) for 6 hours. Patients were monitored for the develo pment of arrhythmias during the first 5 postoperative days. Results. T he incidence of sinus tachycardia and ventricular arrhythmias were sim ilar between groups. Triiodothyronine-treated patients had a lower inc idence of atrial fibrillation (24% versus 46%; p = 0.009), and fewer r equired cardioversion (0 versus 6; p = 0.012) or anticoagulation (2 ve rsus 10; p = 0.013) during hospitalization. Six patients in the T3 gro up versus 16 in the placebo group required antiarrhythmic therapy at d ischarge (p 0.019). Conclusions. Perioperative T3 administration decre ased the incidence and need for treatment of postoperative atrial fibr illation.