Guanxinjing capsule in the treatment of chronic stable angina: study protocol for a randomized controlled trial

BACKGROUND: Stable angina is a common cardiovascular disease with high mortality and a poor prognosis. Although there are various interventions against stable angina, none are able to significantly reduce the mortality rate. Guanxinjing capsule (GXJ) is made from the classical Chinese prescription Xuefuzhuyutang (血府逐瘀汤). Both basic research and clinical studies have shown that GXJ can relieve the symptoms of angina, but currently, the effects of GXJ lack high-quality clinical evidence. The aim of this study was to evaluate the clinical effectiveness and safety of GXJ compared with placebo. METHODS/DESIGN: This multicentre, blinded, randomized trial will be conducted with a total of 120 participants diagnosed with chronic stable angina (Qi deficiency and blood stasis syndrome). Using a central randomization system, participants will be randomized (1:1) into groups receiving either GXJ or placebo for 8 weeks. After a 2-week run-in period, eligible patients will receive either GXJ or placebo (4 pills, three times daily) for 8 weeks in addition to conventional treatment. The primary outcomes include changes in the total exercise time on exercise tolerance tests and changes in the integral scores of angina symptoms. The secondary outcome measures include changes in the maximal estimated workload, changes in time to a 1 mm ST-segment depression or raise, changes in the time to onset of angina during exercise tolerance testing, changes in the total score of traditional Chinese medicine syndrome, and changes in the total score of the Generalized Anxiety Disorder 7-item assessment between baseline and week 8. Other outcome measures will also be assessed. All exercise tolerance tests use a standard Bruce multistage exercise test protocol. Adverse events will be monitored throughout the trial. DISCUSSION: This study will investigate whether GXJ can alleviate clinical symptoms, increase the angina-free walking time, and improve quality of life in patients with chronic stable angina (Qi deficiency and blood stasis syndrome). The results of this study will provide clinical evidence for the application of GXJ to the treatment of stable angina. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1800014258. Registered on 2 January 2018. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13063-018-2950-7) contains supplementary material, which is available to authorized users.