1. Unit of Cardiovascular and Nutritional Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden (S.C.L.).
2. Department of Surgical Sciences, Uppsala University, Uppsala, Sweden (S.C.L., K.M.).
3. Department of Medicine, Karolinska Institutet, Huddinge, Stockholm, Sweden (N.D.).
4. Division of Arrhythmia, Karolinska University Hospital, Stockholm, Sweden (N.D.).