1 Department of Cardiology, Liaocheng People's Hospital affiliated to Shandong University, Jinan 250012, PR China; Clinical School of Taishan Medical University, Liaocheng 252000, PR China.
2 Department of Cardiology, Liaocheng People's Hospital affiliated to Shandong University, Jinan 250012, PR China; Clinical School of Taishan Medical University, Liaocheng 252000, PR China. Electronic address: yaohc66@126.com.