1. Department of Medicine, Dow University of Health Sciences, Mission Rd, Saddar, 74200 Karachi, Pakistan
2. Department of Medicine, Ziauddin University, Shahrah-e-Ghalib Rd, Block 6 Clifton, 74200 Karachi, Pakistan
3. Department of Medicine, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA
4. Division of Cardiology, Duke University Medical Center, 2301 Ervin Rd, NC 27710, Durham, USA
5. Duke Clinical Research Institute, NC 27701, Durham, USA