1. Unité de Recherche en Pneumologie, Centre de Pneumologie de l’Hôpital Laval, and
2. Institut de Cardiologie de Québec, Hôpital Laval, Université Laval, Quebec, Canada G1V 4G5;
3. Department of Medicine, Division of Cardiology, Duke University Medical Center, Durham, North Carolina 27710; and
4. Department of Medicine, McMaster University Medical Centre, Hamilton, Ontario, Canada L8N 3Z5