1. Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital , Beijing 100048 , China
2. Cardiovascular Center, Beijing Tongren Hospital, Capital Medical University , Beijing 100730 , China
3. Department of Cardiology, Kailuan General Hospital , Tangshan 063000 , China
4. School of Medicine, Nankai University , Tianjin 300071 , China