To the Editor: In a recent issue of Circulation , Zaman et al1 report a model for the preoperative risk stratification of patients at risk for developing atrial fibrillation (AF) after isolated coronary artery bypass grafting (CABG). They studied 326 patients prospectively and demonstrated that prolonged signal-averaged P-wave duration (SAPD), advanced age, and male sex identified patients at a high risk for post-CABG AF. Moreover, there was an incremental increase in risk for patients with >1 of these 3 variables. We agree with the authors that a predictive model for patients at risk for post-CABG AF could be useful for the management of this common complication. Advanced age was identified as an important predictor, and this has been consistently reported as a risk factor in prior studies.2 3 Male sex was identified as a risk in one prior report but not in the majority of other existing studies.4 The authors also highlight the …