1. Greater Brisbane Clinical School, Medical School, The University of Queensland , Chermside, QLD 4032 , Australia
2. Department of Cardiology, The Prince Charles Hospital , Chermside, QLD 4032 , Australia
3. The Wollongong Hospital , Wollongong, NSW 2500 , Australia
4. Department of Thoracic Medicine, The Prince Charles Hospital , Chermside, QLD 4032 , Australia