Impaired cardiac autophagy in patients developing postoperative atrial fibrillation

Objectives: Postoperative atrial fibrillation (POAF) is a common complication after on-pump heart surgery. Several histologic abnormalities, such as interstitial fibrosis and vacuolization, have been described in atrial samples from patients developing POAF. This ultrastructural remodeling has been associated with the establishment of a proarrhythmic substrate. We studied whether atrial autophagy is activated in patients who develop POAF. Methods: A total of 170 patients in sinus rhythm who had undergone elective coronary artery bypass grafting were included. Systemic inflammatory markers were measured at baseline and 72 hours after surgery. During the procedure, samples of the right atrial appendages were obtained for evaluation of remodeling by light and electron microscopy. Protein ubiquitination and autophagy-related LC3B processing were assessed by Western blot. Results: Of these patients, 22% developed POAF. The level of high-sensitivity C-reactive protein, fibrosis, inflammatio