Kuanxiong Aerosol (KXA)(CardioVent®), consisting of Asarum sieboldii Miq. oil, Santalum album L. oil, Alpinia officinarum Hance oil, Piper longum L. oil and borneol, seems to relieve the symptoms of chest pain and serve as a supplementary treatment for prehospital chest pain in emergency department.This randomized controlled trial aimed to determine the clinical effect and safety of KXA for patients with prehospital chest pain.A total of 200 patients were recruited from Guangdong Provincial Hospital of Chinese Medicine and randomly divided into KXA group (n = 100) and Nitroglycerin Aerosol (NA) group (n = 100) by SAS 9.2 software. All patients were treated with standardized Western medicine according to the pre-hospital procedure. The experimental group and NA group was additionally treated with KXA and NA respectively. The primary outcome was the relieving time of prehospital chest pain (presented as relief rate) after first-time treatment. The secondary outcomes included the evaluation of chest pain (NRS scores, degree of chest pain, frequency of chest pain after first-time treatment), efficacy in follow-up time (the frequency of average aerosol use, emergency department visits, 120 calls, medical observations and hospitalization at 4 weeks, 8 weeks, 12 weeks), alleviation of chest pain (Seattle angina questionnaire, chest pain occurrence, and degree of chest pain at 12-weeks treatment) and the change of TCM symptoms before and after 12-weeks treatment. In addition, the safety of KXA was also assessed by the occurrence of adverse events. The database was created using Epidata software, and statistical analysis was conducted by SPSS 23.0 software.A total of 194 participants finally completed the trial, the results showed that after first-time treatment, KXA had a higher relief rate (72.2%) of chest pain within 30 min than that of NA group (59.4%, p = 0.038), KXA group had a lower degree of chest pain (p = 0.005), lower NRS score (p = 0.011) and higher reduction of NRS score (p = 0.005) than the NA. In the follow-up period, KXA group decreased the frequency of 120 call better than that of NA group at 4 weeks (p = 0.040), but KXA had a similar efficacy as NA in the improvement on the of frequency of chest pain, aerosol use, emergency department visits, 120 call, medical observation and hospitalization at 4 weeks, 8 weeks and 12 weeks (p>0.05). There also had no difference between the two groups on the occurrence of chest pain, degree of chest pain, physical limitation, angina stability, treatment satisfaction, and disease perception between the two groups at 12 weeks (p>0.05). In addition, KXA and NA both improved the patient's chest pain, but not the TCM symptoms. In terms of safety, KXA showed similar safety as NA in this study.KXA relieved prehospital chest pain faster than NA and had a better remission effect on the prehospital chest pain than that of the NA group in short-period. In long-period, KXA showed similar efficacy on the improvement of prehospital chest pain as NA. KXA may be a safe and reliable therapy for prehospital chest pain.Copyright © 2023. Published by Elsevier GmbH.