Free triiodothyronine: a novel predictor of postoperative atrial fibrillation.
OBJECTIVE
Despite improved perioperative management, atrial fibrillation (AF) after coronary artery bypass grafting (CABG) remains a relevant clinical problem, whose pathogenetic mechanisms remain incompletely explained. A reduced incidence of postoperative AF has been described in CABG patients receiving IV tri-iodothyronine (T3). This study was designed to define the role of thyroid metabolism on the genesis of postoperative AF.


RESULTS
Free T3 (fT3), free thyroxine (fT4), and thyroid stimulating hormone were assayed at admission in 107 consecutive patients undergoing isolated CABG surgery. Patients with thyroid disease or taking drugs known to interfere with thyroid function were excluded. A preoperative rhythm other than sinus rhythm was considered an exclusion criterion. Thirty-three patients (30.8%) had postoperative AF. An older age (P=0.03), no therapy with beta-blockers (P=0.08), chronic obstructive pulmonary disease (P=0.08), lower left ventricle ejection fraction (P=0.09) and lower fT3 concentration (P=0.001), were univariate predictors of postoperative AF. On multivariate analysis, low fT3 concentration and lack of beta-blocking therapy were independently related with the development of postoperative AF (odds ratio, OR, 4.425; 95% confidence interval, CI, 1.745-11.235; P=0.001 and OR 3.107; 95% CI 1.087-8.875; P=0.03, respectively). Postoperative AF significantly prolonged postoperative hospital stay (P=0.002).


CONCLUSIONS
Low basal fT3 concentration can reliably predict the occurrence of postoperative AF in CABG patients.
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000097:blood / Q000175:diagnosis / Q000209:etiology*; D015415:Biomarkers / Q000097:blood; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007902:Length of Stay; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome; D014284:Triiodothyronine / Q000097:blood*
D000319:Adrenergic beta-Antagonists; D015415:Biomarkers; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine