Evaluating the efficacy and safety of oral triple sequential combination therapy for treating patients with pulmonary arterial hypertension: A multicenter retrospective study oleh Qin‐Hua Zhao, Jun Chen, Fa‐Dong Chen, Hong‐Yun Ruan, Wei Zhang, Yan‐Li Zhou, Qi‐Qi Wang, Xiao‐Ling Xu, Ke‐Fu Feng, Jian‐Zhou Guo, Su‐Gang Gong, Rui‐Feng Zhang, Lan Wang