Guanxinjing capsule in the treatment of chronic stable angina: study protocol for a randomized controlled trial oleh Ying Tian, Junhua Zhang, Yingqiang Zhao, Jingyuan Mao, Linping Zhu, Rui Gao, Xuemei Wang, Mingjun Zhu, Lihong Ma, Mengyu Zhao, Wenke Zheng