Changes of thyroid hormones at patients undergoing isolated coronary artery bypass surgery and their relationship with arrythmia

Objective: Coronary artery disease is a very common and serious health problem and its effects over life quality is quite important. Surgery is one of the most important treatment options. Arrythmias after cardiac surgery may have multiple etiologic causes. The aim of this study is to insvestigate changes of thyroid hormones and its relationship with arrythmias after cardiac surgery.Methods: Between the dates August 2012 and January 2013 at the Turgut Özal Medical Center; eighty four euthyroidic isolated coronary artery disease patients were included in this study. Patients without new-onset arrythmia or atrial fibrillation were included in Group 1 (n=66) and patients with new-onset arrythmia or atrial fibrillation were included in Group 2 (n=18). Exclusion criteria were; emergency operations, patients with renal or hepatic dysfunctions, low ejection fraction (<30%), known thyroid disease or operation, additional cardiac or aortic surgery, malignancy, cachexia, patients who received amiodarone or stayed in an intensive care unit other than coronary causes in last six months. After cardiac surgery, blood samples were collected at the time of arrival to intensive care unit (D0), 24th hour (D1), 48th hour (D2), 72th hour (D3) and 96th hour.Results: All of the patients were euthyroidic preoperatively. Arrythmia was detected at 21,43% patients. Twelve patients had atrial fibrillation and six patients had ventricular arrythmia. Postoperative second day was the most common day for arrythmia.fT3 values were lower than preoperative values at both groups. This fall was significantly important at postoperative second day (p=0,003). When intra-group falls were compared fT3 values were lowering at both groups. This fall was more at arrythmia group and fT3 fall at D2 term (p=0,036)was especially important.fT4 values were higher than preoperative values at both groups. When intra-group rises were compared fT4 values were rising at both groups. This rise was more at arrythmia group and fT4 rise at D1 term (p=0,022)was especially important.Conclusion: Fall of fT3 values at arrythmia group (Group 2) were greater. This is especially important because it is more significant at postoperative second day and this is the most common day for arrythmia after cardiac surgery. There is a rise at fT4 values and this is higher at arrythmia group. These relatively high values may be mimicing hyperthyroidism and may be considered as a predisposition for arrythmia and atrial fibrillationWell-planned prospective, controlled, randomised studies with larger groups including on-pump and off-pump surgery are required for deciding affects cardiopulmonary bypass and surgery.Key words: Coronary artery disease, Cardiopulmonary bypass, Thyroid hormones, Euthyroid sick syndrome