Atrial fibrillation (AF) is found in 40 to 60% of patients who require mitral valve surgery, with the treatment of choice being the maze procedure accompanied by mitral valve repair where it is technically feasible.  The efficacy of the maze operation in patients undergoing MV replacement is unclear, in that anticoagulation after MV replacement may be sufficient to protect against CVAs without restoration of sinus rhythm, and the procedure itself may be less effective in the more advanced valve pathology that is not amenable to repair.

However, even in anticoagulated patients, it may be beneficial to reduce AF recurrence as it may additionally reduce stroke risk and increase patient exercise tolerance and overall quality of life.  In this single-centre retrospective study of 435 patients undergoing mitral valve surgery and the maze procedure between 1999 and 2007, 226 underwent mitral repair and 209 underwent valve replacement (the large majority of which were mechanical), and were subsequently followed up for a median of 40.6 months with regular ECGs and 24 hour Holter monitoring if there were any symptoms of AF reported.  The groups were generally well matched at baseline although there were a significantly higher number of patients with rheumatic valve disease in the replacement group.  427 patients were deemed ‘early survivors’ and in these individuals the maze procedure was highly successful, with only 64 individuals having late recurrence with no significant difference found between those who had repair and those who had replacement.  The factors that were associated with recurrence were age greater than 60, fine atrial fibrillation wave form and preoperative atrial dimension greater than 60mm regardless of whether the patient had concomitant atrial reduction surgery, factors which have all been highlighted in previous studies.  The results of this study therefore suggest that the maze procedure is equally effective at suppressing AF regardless of the type of valve procedure undertaken.  The authors are unable to comment on whether this actually reduces hard clinical end-points such as CVAs or increases quality of life, due to the small numbers in the study.  An adequately powered prospective study to examine the true benefits of this procedure would therefore seem warranted.

Kim JB, Yun TJ, Chung CH, Choo SJ, Song H and Lee JW.  Long-term outcome of modified maze procedure combined with mitral valve surgery: Analysis of outcomes according to type of mitral valve surgery.  J Thorac Cardiovasc Surg 2010;139:111-117.

Journals scanned

American Journal of Medicine; American Journal of Physiology: Heart and Circulatory Physiology; Annals of Emergency Medicine; Annals of Thoracic Surgery; Archives of Internal Medicine; BMJ; Chest; European Journal of Cardiothoracic Surgery; JAMA; Journal of Clinical Investigation; Journal of Diabetes and its Complications; Journal of Immunology; Journal of Thoracic and Cardiovascular Surgery; Lancet; Nature Medicine; New England Journal of Medicine; Pharmacoeconomics; Thorax

Reviewers

Dr Alistair C Lindsay, Dr Jonathan Spiro, Dr Hussain Contractor