Is tongxinluo more effective than isosorbide dinitrate in treating angina pectoris? A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND

Tongxinluo (TXL), consisting of 12 Chinese Materia Medica items catalogued in the Chinese Pharmacopoeia, is commercially available in China, South Korea, and Russia. Hundreds of randomized clinical trials (RCTs) on TXL in treating cardiovascular diseases were conducted and published in China. This study provides a comprehensive Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-compliant systematic review with sensitivity and subgroup analyses to evaluate the evidence about whether TXL is more effective than isosorbide dinitrate (ISDN) in treating ischemic heart disease, particularly angina pectoris.

METHODS

RCTs published between 1996 and 2010 on TXL versus ISDN in treating angina pectoris for at least 4 weeks were retrieved from eight bibliographical databases (e.g., MEDLINE,(®) PubMed, Chinese National Knowledge Infrastructure, Cochrane Library, and WanFang Data). The quality of RCTs was assessed with the Jadad scale. Meta-analysis was performed to estimate the overall effects based on symptomatic and electrocardiographic (ECG) improvements. Subgroup analysis, sensitivity analysis, and meta-regression were conducted on the study characteristics of RCTs.

RESULTS

Twenty (20) RCTs with a total of 1936 participants were included after eligibility assessment. The Jadad score of all included studies was 2. The means of summary odds ratios (ORs) for comparing TXL and nitrates were 3.30 (95% confidence interval [CI] 2.37-4.58) by symptoms (n=20) and 2.38 (95% CI 1.846-3.09) by ECG (n=18). There was a significant correlation of ORs between symptoms and ECG (ρ=0.77 and p=0.00026). Subgroup analysis, sensitivity analysis, and meta-regression found no significant difference in overall effects among all study characteristics except the years of publication (p=0.0409).

CONCLUSIONS

The meta-analysis of 20 eligible RCTs demonstrates moderate evidence that TXL is more effective than ISDN for treating angina pectoris. This result warrants further RCTs of multicenters/countries, larger sample sizes, and higher quality.