1 Department of Medicine, Division of Cardiology, Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec, Canada.
2 University of British Columbia, Vancouver, British Columbia, Canada.
3 Department of Medicine, Division of Cardiology, Institut de Cardiologie de Montréal, Université de Montréal, Montréal, Québec, Canada; Electrophysiology Service, Montreal Heart Institute, Montreal, Quebec, Canada. Electronic address: lmacle@mac.com.