CORONARY slow flow phenomenon (CSFP) in patients with angina was significantly improved with Shexiang Tongxin Dropping Pill (STDP), according to new phase IV trial data, supporting its efficacy and safety in routine clinical practice.
CSFP is characterised by delayed coronary blood flow in the absence of obstructive coronary artery disease and is associated with recurrent angina, impaired quality of life, and increased healthcare use. Treatment options remain limited, making effective pharmacological strategies a key unmet need in cardiovascular care.
Improved Coronary Slow Flow in Angina Patients
In this multicentre, randomised, controlled study, investigators evaluated the efficacy and safety of STDP in 200 adults with angina and CSFP. Participants were enrolled between July 2016 and August 2020 and randomly assigned to receive STDP or placebo. The primary outcome was change in corrected TIMI frame count (CTFC), an angiographic measure of coronary blood flow.
The results showed that patients receiving the STDP experienced significant reductions in CTFC in both the left anterior descending artery and left circumflex artery (both p<0.01), indicating faster coronary flow. No significant changes were observed in the placebo group. Between-group differences were significant for both the left anterior descending artery (p=0.008) and left circumflex artery (p=0.044).
Importantly, the therapy was well tolerated, with no major safety concerns reported during the trial. These findings suggest that STDP improved coronary microvascular perfusion while maintaining an excellent safety profile.
CSFP is thought to involve microvascular dysfunction, endothelial impairment, and inflammation. By improving coronary blood flow without increasing adverse events, the intervention may address key mechanisms underlying angina symptoms in this population.
Strengths, Limitations, and Future Directions
The trial’s strengths included its randomised, double-blind design and assessment of both angiographic coronary flow and clinical measures, including angina symptoms and electrocardiographic parameters, over two months of treatment.
However, the authors highlighted a baseline imbalance in high-density lipoprotein levels between groups, which may have influenced outcomes, and recommended larger studies with multivariable lipid adjustment to clarify the independent effects of STDP. Limitations also included imprecise angina symptom quantification at enrolment, and a study population limited to Chinese patients, supporting the need for refined symptom tools and validation in more diverse cohorts.
Nevertheless, these data positioned STDP as a promising option for angina patients with CSFP.
Reference
Li N et al. Efficacy and safety of Shexiang Tongxin pill for coronary slow flow in angina patients. npj Cardiovasc Health. 2026; DOI:10.1038/s44325-025-00098-y.
