1. Department of Cardiovascular Medicine, John Hunter Hospital , Lookout Road, Newcastle 2305 , Australia
2. School of Medicine and Public Health, University of Newcastle , University Drive, Newcastle 2308 , Australia
3. Hunter Medical Research Institute , Kookaburra Circuit, Newcastle 2305 , Australia
4. Department of Cardiology, Gosford Hospital , 75 Holden Street, Gosford 2250 , Australia
5. Department of Medicine, Tamworth Rural Referral Hospital , Dean Street, Tamworth 2340 , Australia
6. Department of Cardiology, Calvary Mater Hospital , 20 Edith Street, Newcastle 2298 , Australia
7. Department of Anaesthesia, John Hunter Hospital , Lookout Road, Newcastle 2305 , Australia