Efficacy and safety of Xinnaoning capsule in treating chronic stable angina (qi stagnation and blood stasis syndrome): Study protocol for a multicenter, randomized, double-blind, placebo-controlled trial

BACKGROUND: Chronic stable angina (CSA) is a cardiovascular disease with high prevalence. At present, drug treatment is still the main measure of stable angina pectoris. Traditional Chinese medicine has a long history in the treatment of CSA. Qi stagnation and Blood stasis syndrome is a common syndrome of CSA. Xinnaoning (XNN) capsule is considered as an effective adjuvant treatment for CSA with the efficacy of promoting qi and blood circulation but lack of high-quality clinical evidence. The purpose of this study is to evaluate the efficacy and safety of XNN capsule compared with placebo by clinical trial. METHODS: This multicenter, randomized, double-blind, placebo-controlled trial will be conducted with a total of 240 participants diagnosed with chronic stable angina (qi stagnation and blood stasis syndrome). The participants will be randomized (1:1) into groups receiving either XNN or placebo for 12 weeks. After a 2-week run-in period, they will receive either XNN or placebo (3 pills, 3 times daily) for 12 weeks on the basis of conventional therapy. The primary outcomes include changes in the integral scores of angina symptoms. The secondary outcome measures include changes in the total score of traditional Chinese medicine syndrome, severity grading of angina pectoris, the number of angina pectoris per week, nitroglycerin dosage, score of seattle angina scale, serum homocysteine, incidence of cardiovascular events. Safety outcomes will also be assessed. Adverse events will be monitored throughout the trial. RESULTS: This study will investigate whether XNN capsule can alleviate clinical symptoms, and improve quality of life of patients with chronic stable angina (qi stagnation and blood stasis syndrome). The results of this study will provide clinical evidence for the application of XNN capsule in the treatment of chronic stable angina. TRIAL REGISTRATION: ClinicalTrials.gov: NCT 03914131.