Study design and rationale of the TXL-CAP trial: a randomized, double-blind, placebo-controlled, multicenter clinical trial assessing the effect of Tongxinluo capsules on the stability of coronary atherosclerotic plaques

Recent clinical trials have demonstrated a protective effect in using traditional Chinese medicine Tongxinluo (TXL) capsule to treat atherosclerosis. However, clinical evidence of the effects of TXL treatment on coronary plaque vulnerability is unavailable. In response, we developed this study to investigate the hypothesis that on the basis of statin therapy, treatment with TXL capsule may stabilize coronary lesions in patients with acute coronary syndrome (ACS). The TXL-CAP study was an investigator-initiated, randomized, double-blind clinical trial conducted across 18 medical centers in China. Patients with ACS aging from 18 to 80 years old who had a non-intervened coronary target lesion with a fibrous cap thickness (FCT) < 100 μm and lipid arc > 90° as defined by optical coherence tomography (OCT) were recruited. A total of 220 patients who met the selection criteria but did not meet the exclusion criteria will be finally recruited and randomized to receive treatment with TXL (n = 110) or placebo (n = 110) for a duration of 12 months. The primary endpoint was the difference in the minimum FCT of the coronary target lesion between TXL and placebo groups at the end of the 12-month follow-up. Secondary endpoints included: (1) changes of the maximum lipid arc and length of the target plaque, and the percentage of lipid, fibrous, and calcified plaques at the end of the 12-month period; (2) the incidence of composite cardiovascular events and coronary revascularization within the 12 months; (3) changes in the grade and scores of the angina pectoris as assessed using the Canadian Cardiovascular Society (CCS) grading system and Seattle angina questionnaire (SAQ) score, respectively; and (4) changes in hs-CRP serum levels. The results of the TXL-CAP trial will provide additional clinical data for revealing whether TXL capsules stabilizes coronary vulnerable plaques in Chinese ACS patients.