Original article
Cardiovascular
Determination of Histopathologic Risk Factors for Postoperative Atrial Fibrillation in Cardiac Surgery

https://doi.org/10.1016/j.athoracsur.2004.12.029Get rights and content

Background

Postoperative atrial fibrillation is one of the most common complications after coronary artery bypass grafting. This study aimed to identify preoperative histopathologic risk factors for the development of postoperative atrial fibrillation.

Methods

One hundred elective coronary artery bypass grafting patients were enrolled into the study. Right atrial tissue from all patients was sampled before cardiopulmonary bypass. Patients were monitored for the occurrence of the postoperative atrial fibrillation. Right atrial tissue samples from the atrial fibrillation group were compared with samples belonging to the patients who remained in sinus rhythm postoperatively. Evaluation for atrial histopathology and myocyte apoptosis included light microscopic and immunohistochemical studies.

Results

Fourteen of 100 patients (14%) developed postoperative atrial fibrillation. On univariate analysis, the only predictor for the development of postoperative atrial fibrillation was chronic obstructive pulmonary disease (p = 0.014). Histologically, larger sized myolytic vacuoles were more common in patients who developed postoperative atrial fibrillation (p = 0.001). The percentage of apoptotic myocytes in each specimen was significantly higher in patients with atrial fibrillation (p = 0.000). Most of the specimens with positive apoptotic staining were also severely myolytic in patients with postoperative atrial fibrillation.

Conclusions

Our results suggest that degree of myolysis and increased apoptotic pattern in right atrial myocardium are significant predictors for the development of postoperative atrial fibrillation. The improvement of preoperative metabolic status of the myocardial cells may reduce the incidence of this common complication.

Section snippets

Material and Methods

One hundred patients undergoing elective CABG and in normal sinus rhythm preoperatively were enrolled in the study. Following approval to conduct the study from the ethical committee of the Marmara University School of Medicine, samples of right atrial appendage tissue (weighing at least 100 mg) from all patients were obtained prior to establishing cardiopulmonary bypass. A circular purse string suture was placed to the base of right atrial appendage for the venous cannulation in all patients.

Results

Postoperative AF was seen in 14 of 100 patients (14%). Mean time for the occurrence of postoperative AF was 45 ± 24.3 hours after cardiac surgery. In univariate analysis, the only independent clinical predictor for the risk of postoperative AF was found to be COPD (p = 0.014; Table 2). None of the independent clinical predictors created a statistical significance for postoperative AF in multivariate analysis. Preoperative beta-blocker therapy did not seem to prevent the occurrence of

Comment

Despite the improvements in myocardial protection, CPB and care of critically ill patients over the last 50 years in cardiac surgery, postoperative AF still remains one of the most common causes of morbidity after CABG [4, 7]. Identifying the patients at risk for postoperative AF after CABG would result in the reduction of both the incidence and undesired clinical consequences related to postoperative AF [13]. Prophylactic treatment of postoperative AF with anti-arrhythmic drugs is not without

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