Forest plot of the odds ratio (OR) of freedom from AF at 6 months, 12 months and endpoint in AF patients undergoing surgical or catheter ablation. The estimate of the OR of each trial corresponds to the middle of the squares and the horizontal line shows the 95% confidence interval (CI). On each line, the number of events as a fraction of the total number randomized is shown for both treatment and control groups. For each subgroup, the sum of the statistics, along with the summary OR, is represented by the middle of the solid diamonds. A test of heterogeneity between the trials within a subgroup is given below the summary statistics. AF, atrial fibrillation; M-H, Mantel-Haenszel.