Atrial Structural Remodeling in Coronary Patients with and without Postoperative Atrial Fibrillation

Structural atrial remodeling alters the substrate and spatiotemporal organization of the atrium in atrial fibrillation. In this paper we proposed: (a) qualitative and quantitative evaluation of structural changes in the atrial myocardium in coronary patients with and without postoperative atrial fibrillation; (b) assessment of the nature of structural changes: reversible and irreversible degeneration or dedifferentiation. The study included 20 coronary patients admitted at Cardiovascular Disease Institute in 2012. The patients were 14 men and 6 women aged between 36 and 74 years. The 20 patients, selected on clinical and laboratory criteria, were 10 patients with postoperative atrial fibrillation and 10 patients with postoperative sinus rhythm. Atrial tissue samples from patients in the atrial fibrillation group were compared with samples from patients who remained in postoperative sinus rhythm. Identifying lesions required optical microscopy examination, using special histological techniques and immunohistochemistry. Both groups developed degenerative and dedifferentiated lesions, but to different extents, values recorded in the postoperative atrial fibrillation being much higher than in the postoperative sinus rhythm patients. Our study indicated that hypertrophy, myocytolysis and fibrosis were defining injuries of the dedifferentiation process and accompanied degenerative alterations in both study groups. This implies that the morphological status of atrial tissue is a major determinant in the postoperative atrial fibrillation development and the improvement of preoperative metabolic status of myocardial cells may reduce the incidence of this common complication.