OBJECTIVETo analyze the relationship between early spontaneous cardioversion of atrial fibrillation (AF) and thyroid hormone metabolism after mitral replacement in patients with rheumatic heart disease, and explore the treatment strategy of early spontaneous cardioversion after mitral valve replacement.

METHODSAccording to the occurrence of cardioversion, 138 patients with mitral valve replacement were divided into conversion group and non-conversion group, and based on the duration of sinus rhythm, the patients in conversion group were divided into < 3 days group and > 3 days group. Triiodothyronine (T3) was detected by radioimmunoassay in all the patients.

RESULTST3 metabolism decreased significantly after the operation in all the patients. Early spontaneous cardioversion of AF occurred 2 h after the operation in 52 cases (37.7%), and 28 (20.3%) of the cases had a duration of sinus rhythm longer than 3 days. T3 was significantly decreased in conversion group and non-conversion group by 44.5% and 58.7% at 2 h, by 40.0% and 52.4% at 24 h and by 28.6% and 37.7% at 72 h after the operation, respectively. The levels of T3 in conversion group was significantly higher than the levels in non-conversion group, and showed no significant variation with the duration of sinus rhythm.

CONCLUSIONEnhancement of T3 levels after mitral valve replacement may increase the probability of early spontaneous cardioversion of AF, but can not affect the duration of sinus rhythm. This finding supports the supplementation of T3 perioperatively in patients undergoing cardiac surgeries.