Controlling Hypertension After Severe Cerebrovascular Event (CHASE): study protocol for a randomized controlled trial oleh Fang Yuan, Fang Yang, Changhu Xue, Kangjun Wang, Qiuwu Liu, Jun Zhou, Feng Fu, Xiaocheng Wang, Wei Zhang, Yi Liu, Kang Huo, Hua Lv, Wen Jiang, on behalf of the CHASE Study Group