1. Department of Cardiology, University Hospitals of North Midlands NHS Trust, Newcastle Rd, Stoke-on-Trent ST4 6QG, UK
2. Department of Cardiology, University Hospitals of Birmingham NHS Trust, Birmingham, UK
3. Chun Shing Kwok is now affiliated to Department of Cardiology, University Hospitals of North Midlands NHS Trust, Stoke-on-Trent, UK
4. William E. Moody is also affiliated to University of Birmingham, Birmingham, UK