title: Interrelationships between serum levels of amiodarone, desethylamiodarone, reverse T3 and the QT interval during long-term amiodarone treatment.
abstract: The interrelationships between serum levels of amiodarone, desethylamiodarone, and reverse T3, and changes in the corrected QT interval (delta QTc) were examined in 22 patients during long-term treatment with amiodarone. At 1, 3, and 6 months of follow-up, the correlation coefficient between serum levels of amiodarone or desethylamiodarone and reverse T3 ranged from 0.01 to -0.2 (p greater than 0.4). At the same time intervals, the correlation coefficient between both amiodarone and desethylamiodarone levels and delta QTc ranged from 0.1 to -0.1 (p greater than 0.6), and the correlation coefficient between reverse T3 and delta QTc also ranged between 0.1 to -0.1 (p greater than 0.5). Substituting percent delta QTc for delta QTc also did not reveal a significant correlation. These data demonstrate that serum levels of reverse T3 cannot be used as a substitute for serum levels of amiodarone in monitoring patients being treated with amiodarone. The absence of a correlation between serum reverse T3 levels and delta QTc suggests that the delay in repolarization which occurs during amiodarone therapy is not secondary to an amiodarone-induced abnormality in thyroid hormone metabolism.
mesh_terms: D000328:Adult; D000368:Aged; D000638:Amiodarone / Q000031:analogs & derivatives / Q000097:blood* / Q000627:therapeutic use*; D001145:Arrhythmias, Cardiac / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology; D001572:Benzofurans / Q000097:blood* / Q000627:therapeutic use*; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors; D014285:Triiodothyronine, Reverse / Q000097:blood*
chemical_list: D001572:Benzofurans; D014285:Triiodothyronine, Reverse; C036116:desethylamiodarone; D000638:Amiodarone