title: Impaired cardiac autophagy in patients developing postoperative atrial fibrillation.
abstract: OBJECTIVE
  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, inflammation, myxoid degeneration, and ubiquitin-aggregates in the atria did not differ between patients with and without POAF. Electron microphotographs of those with POAF showed a significant accumulation of autophagic vesicles and lipofuscin deposits. Total protein ubiquitination was similar in the patients with and without POAF, but LC3B processing was markedly reduced in those with POAF, suggesting a selective impairment in autophagic flow.
  
  
  CONCLUSIONS
  This study provides novel evidence that ultrastructural atrial remodeling characterized by an impaired cardiac autophagy is present in patients developing POAF after coronary artery bypass surgery.
authors: Centro Estudios Moleculares de Celula, Facultad Ciencias Quimicas y Farmaceuticas, Universidad de Chile, Santiago, Chile.
authors: Lorena
authors: L
authors: Garcia
authors: Hugo E
authors: HE
authors: Verdejo
authors: Jovan
authors: J
authors: Kuzmicic
authors: Ricardo
authors: R
authors: Zalaquett
authors: Sergio
authors: S
authors: Gonzalez
authors: Sergio
authors: S
authors: Lavandero
authors: Ramon
authors: R
authors: Corbalan
mesh_terms: D000368:Aged; D020517:Atrial Appendage / Q000378:metabolism / Q000473:pathology* / Q000648:ultrastructure; D001281:Atrial Fibrillation / Q000209:etiology* / Q000378:metabolism / Q000473:pathology*; D001343:Autophagy; D001706:Biopsy; D015153:Blotting, Western; D002097:C-Reactive Protein / Q000032:analysis; D002677:Chile; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D005260:Female; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood; D016015:Logistic Models; D008297:Male; D008854:Microscopy, Electron; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008875:Middle Aged; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome; D054875:Ubiquitination
chemical_list: D018836:Inflammation Mediators; C502070:MAP1LC3B protein, human; D008869:Microtubule-Associated Proteins; D002097:C-Reactive Protein