In patients with an enlarged left atrium does left atrial size reduction improve maze surgery success?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was: In [adults undergoing a maze procedure for atrial fibrillation (AF)], [does left atrial size reduction] compared to [maze surgery alone] improve [maze surgery success]? A total of 58 papers were found using the reported search, of which eight represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Four out of eight papers compared a volume reduction technique as an adjunct to the maze procedure to a maze procedure alone--all four papers reported that atrial volume reduction significantly increased restoration of sinus rhythm: 89.3% vs. 67.2%, P<0.001; 85% vs. 68%, P<0.05; 84% vs. 68%, P<0.05; 90% vs. 69%, P<0.05. Three out of eight papers had no control group but reported good rates of sinus rhythm restoration at last follow-up--90%, 92% and 89%, respectively--despite the study population including atrial enlargement, a risk factor for failure of a maze procedure. One paper reported no benefit of an atrial reduction plasty in patients with a left atrium (LA) >70 mm. An enlarged LA is a risk factor for failure of a maze procedure, and various models of AF suggest that reducing atrial mass and/or diameter may help to abolish the re-entry circuits underlying AF. Furthermore, AF is uncommon when left atrial diameter is <40 mm, so there is at least some physiological basis for atrial reduction surgery in aiding the success of a maze procedure. The evidence suggests that patients with an enlarged (≥ 55 mm) or giant (≥ 75 mm) LA who are at risk of failing to obtain sinus conversion after a standard maze procedure may derive benefit from concomitant atrial reduction surgery using either a tissue excision or a tissue plication technique. However, the evidence is not strong since the papers available are not readily comparable owing to substantial variations in the populations and procedures involved. We therefore, emphasise the need for prospective randomised studies in this area.