Meta-analysis of clinical outcomes of maze-related surgical procedures for medically refractory atrial fibrillation.

OBJECTIVE Although maze-related surgical procedures have shown success at eliminating atrial fibrillation, published controlled studies have generally been too small to detect clinically significant differences in morbidity and mortality. We pooled available studies to determine whether a simultaneous maze procedure reduces the risk of stroke or death in patients with chronic or paroxysmal atrial fibrillation who receive mitral valve surgery. Secondary outcomes included post-operative bleeding and need for pacemaker. METHODS Our systematic review identified four randomized controlled trials and six retrospective comparative studies that met minimum quality criteria. We conducted meta-analyses of clinical outcomes using Cohen's h, a statistic appropriate for analysis of infrequent events. RESULTS The findings suggest that maze may reduce stroke risk but also increase the need for pacemaker implantation, as well as increase the risk of post-operative bleeding unless radiofrequency ablation is used. However, the statistically significant findings for stroke, need for pacemaker, and post-operative bleeding were overturned by sensitivity analysis, indicating that the findings are not robust. CONCLUSION The literature evaluating maze clinical outcomes suffers from several shortcomings, particularly small sample sizes and selection bias. However, weak evidence supports a reduction in stroke rates and an increase in need for pacemakers among patients receiving the maze procedure. Radiofrequency maze may avoid an excess risk of post-operative bleeding associated with maze incisions. Larger, well-designed RCTs are needed to confirm these findings and evaluate outcomes such as survival and quality of life.