1. Robertson Centre for Biostatistics & Clinical Trials, University of Glasgow, Glasgow, UK
2. National Heart & Lung Institute, Royal Brompton & Harefield Hospitals, Imperial College, London, UK
3. Department of Cardiology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
4. Department of Heart Diseases, Wroclaw Medical University, Centre for Heart Diseases, Military Hospital, ul.Weigla 5, 50-981 Wroclaw, Poland