Subclinical Hypothyroidism Might Increase the Risk of Transient Atrial Fibrillation After Coronary Artery Bypass Grafting

Background. Some studies have proposed that subclinical hypothyroidism (SCH) has adverse effects on the cardiovascular system, but little is known about the effect on patients undergoing cardiovascular operations. We examined the influence of preoperative SCH on postoperative outcome in patients undergoing coronary artery bypass grafting (CABG). Methods. Among patients who underwent CABG between July 2005 and June 2007 at Seoul National University Bundang Hospital, 224 with normal thyroid function and 36 with SCH were enrolled. Preoperative risks and postoperative outcomes were evaluated prospectively without thyroid hormone replacement. Results. There were no significant differences in primary outcomes (major adverse cardiovascular events) and secondary outcomes such as wound problems, mediastinitis, leg infection, respiratory complications, delirium, or reoperation during the same hospitalization. However, patients with SCH had a higher incidence of postoperative atrial fibrillation than those with normal thyroid function after adjustment for age, gender, body mass index, and other independent variables such as emergency operation, the use of cardiopulmonary bypass, combined valvular operation, preoperative creatinine levels, left ventricular systolic dysfunction, and nonuse of beta-blockers (45.5% vs 29%; odds ratio, 2.552; 95% confidence interval, 1.117 to 5.830; p = 0.026). Conclusions. SCH appears to influence the postoperative outcome for patients by increasing the development of postoperative atrial fibrillation. However, it is still unproven whether preoperative thyroxine replacement therapy for patients with SCH might prevent postoperative atrial fibrillation after CABG. (Ann Thorac Surg 2009; 87: 1846-52) (C) 2009 by The Society of Thoracic SurgeonsBiondi B, 2008, ENDOCR REV, V29, P76, DOI 10.1210/er.2006-0043RANASINGHE AM, 2006, CIRCULATION, V114, P245Auer J, 2005, J CARDIAC SURG, V20, P425, DOI 10.1111/j.1540-8191.2005.2004123.xCreswell LL, 2005, CHEST, V128, p28SKokkonen L, 2005, J CARDIOTHOR VASC AN, V19, P182, DOI 10.1053/j.jvca.2005.01.028Ripoli A, 2005, J AM COLL CARDIOL, V45, P439, DOI 10.1016/j.jacc.2004.10.044Sirlak M, 2004, EUR J CARDIO-THORAC, V26, P720, DOI 10.1016/j.ejcts.2004.07.003Biondi B, 2004, ENDOCRINE, V24, P1Steinberg JS, 2004, J AM COLL CARDIOL, V43, P1001, DOI 10.1016/j.jacc.2003.12.033Fazio S, 2004, RECENT PROG HORM RES, V59, P31Luepker RV, 2003, CIRCULATION, V108, P2543, DOI 10.1161/01.CIR.0000100560.46946.EACerillo AG, 2003, EUR J CARDIO-THORAC, V24, P487, DOI 10.1016/S1010-7940(03)00396-8Cappola AR, 2003, J CLIN ENDOCR METAB, V88, P2438, DOI 10.1210/jc.2003-030398Iervasi G, 2003, CIRCULATION, V107, P708, DOI 10.1161/01.CIR.0000048124.64204.3FHill LL, 2002, J CARDIOTHOR VASC AN, V16, P483, DOI 10.1053/jcan.2002.31088Crystal E, 2002, CIRCULATION, V106, P75, DOI 10.1161/01.CIR.0000021113.44111.3ESurgenor SD, 2001, ANESTH ANALG, V92, P596Klein I, 2001, NEW ENGL J MED, V344, P501Ascione R, 2000, CIRCULATION, V102, P1530Tamis JE, 2000, CLIN CARDIOL, V23, P155Hogue CW, 2000, ANN THORAC SURG, V69, P300Biondi B, 1999, J CLIN ENDOCR METAB, V84, P2064BOSCH RF, 1999, AM J PHYSIOL, V277, P211Ommen SR, 1997, NEW ENGL J MED, V336, P1429Broderick TJ, 1997, THYROID, V7, P133Klemperer JD, 1996, ANN THORAC SURG, V61, P1323Weisel RD, 1996, ANN THORAC SURG, V61, P1328KLEMPERER JD, 1995, NEW ENGL J MED, V333, P1522TEIGER E, 1993, EUR HEART J, V14, P629SALTER DR, 1992, J CARDIAC SURG, V7, P363OCONNOR GT, 1991, JAMA-J AM MED ASSOC, V266, P803FRIEDEWA.WT, 1972, CLIN CHEM, V18, P499