1. Department of Cardiology, Dorset County Hospital, Dorchester, DT1 2JY, UK
2. British Heart Foundation Centre for Cardiovascular Science, University of Edinburgh, EH16 4TJ, UK
3. Christchurch Heart Institute, University of Otago, PO Box 4345, Christchurch, 8140, New Zealand
4. British Heart Foundation Cardiovascular Research Centre, University of Leicester, LE1 7RH, UK