Aim: Chronic atrial fibrillation (AF) is characterized by a severe contractile dysfunction and myolysis, which develops progressively. Myolysis and the remodelling of the cellular ultrastructure is associated with the replacement of sarcomeres by glycogen. The aim of our study was to determine if myolysis is characterized by a reduction in actin concentration.
Methods: Right atrial samples from 18 patients undergoing elective cardiac surgery were excised and immediately frozen in liquid nitrogen. Eight patients had chronic AF (>3 months) and 10 patients were in sinus rhythm (SR). Actin concentration was determined by sodium dodecyl sulfate-polycrylamide gel electrophoresis (SDS-PAGE), Western blot and quantified by optical densitometry.
Results: Immunoblot analysis demonstrated actin expression in all hearts. In myocardial samples from patients with chronic AF we found a 2.1 fold reduction in actin expression. (P<0.001)
Conclusion: The decrease in actin concentration via myolysis, might decrease energy consumption and be an additional mechanism for contractile dysfunction in chronic AF.