| |
| Date: 09-30-2015 | HC# 041555-529 |
Sun T, Wang X, Xu H. Ginkgo biloba extract for angina pectoris: A systematic review. Chin J Integr Med. July 2015;21(7):542-550.
Angina pectoris (AP) is characterized by chest pain that typically spreads to the shoulder, arm, and neck. It is caused by inadequate blood supply to the heart. In vitro studies indicate that ginkgo (Ginkgo biloba, Ginkgoaceae) extract or its constituents may scavenge oxygen free radicals, antagonize platelet-activating factor, inhibit platelet aggregation, and inhibit arterial thrombosis. These actions could have a positive effect on AP. According to the authors, the scientific literature evaluating the effect of ginkgo on coronary heart disease has not been systematically reviewed. Hence, the purpose of this systematic review was to evaluate the efficacy and safety of ginkgo in the treatment of AP.
The following databases were searched from inception through December 2012: PubMed/MEDLINE, ProQuest Health and Medical Complete, Springer, Elsevier, ProQuest Dissertations and Theses, Wanfang Data, China National Knowledge Infrastructure (CNKI), the VIP database, and the Chinese databases China Biology Medicine (CBM) and Chinese Medical Citation Index (CMCI). The keywords were a combination of the following in English and Chinese: "ginkgo biloba extract," "ginkgo biloba," "EGb," "EGb761," "LI1370," "ginkgo preparation," "angina pectoris," "angina," "coronary heart disease," and "coronary artery disease." Included studies had the following criteria: (1) published or unpublished randomized, controlled trials (RCTs) that treated AP with ginkgo extract; (2) patients had any stage of AP; (3) ginkgo treatment was used alone, combined with conventional pharmaceuticals, or combined with Chinese patent medicine; (4) treatment duration was ≥ one month; and (5) the primary outcome measures were cardiac death and adverse events (AEs) occurring in ≥ six months of follow-up. Secondary outcome measures included angina relief, cardiac function improvement, electrocardiogram (ECG) improvement, and quality of life related to health. Excluded studies did not identify the control group or had a sample size of < 20 patients. Methodological quality of the studies was evaluated with a table of risk of bias provided by RevMan 5.1.0.
A total of 551 studies were identified, and 23 met the inclusion criteria. Overall, the methodological quality of the studies was poor. All included studies were conducted and published in China. There were a total of 2529 patients with AP; the average age in the studies ranged from 38-81 years. The study population sizes ranged from 60-328 patients. Nine studies evaluated ginkgo leaf extract combined with conventional treatment versus the conventional treatment, seven studies compared ginkgo leaf extract with conventional pharmaceuticals, and seven studies compared ginkgo leaf extract with Chinese patent medicine. In this review, a number of different Chinese ginkgo mono- and combination products (oral and parenteral) at different doses were used.
Ten studies measured angina relief (n=986 patients). Only four of the studies reported a statistically significant improvement in angina relief. The authors were able to pool the data from two of the studies that reported an improvement, and the pooled data showed a significant improvement in angina relief (P value not reported).
Seven studies showed a significant improvement in ECG after ginkgo treatment (P value not reported). It is unclear whether this improvement is compared with baseline or control. Two studies were pooled and showed that ginkgo ("Shuxuening tablets") produced a significant improvement in ECGs compared with control ("compound salvia tablets"). Another two studies were pooled and showed that ginkgo ("Xingding injection" or "Yiyou injection" [both uncharacterized]) combined with a variety of conventional pharmaceuticals produced a significant improvement in ECGs compared with control (the matching pharmaceuticals). It is unclear how the authors were able to combine the data from these two studies since the ginkgo compounds and pharmaceuticals differ between the studies.
Only one study evaluated ejection fraction, and reported a significant effect of ginkgo ("Shuxuening tablets") on improving ejection fraction. It is unclear whether this improvement was compared with baseline or control (P value not reported). However, the same study was also the only one that evaluated cardiac index, and there was a significant improvement in cardiac index in patients receiving ginkgo compared with control ("compound salvia tablets") (P value not reported).
Two studies measured stroke volume, and both showed a significant improvement. One of these reported a significant effect of ginkgo ("Shuxuening tablets") on improving ejection fraction. It is unclear whether these improvements were compared to baseline or control (P values not reported).
Two studies evaluated cardiac output. One study reported that there was a significant improvement in cardiac output in patients receiving ginkgo ("Shuxuening tablets") compared with control ("compound salvia tablets") (P value not reported). The second study reported that there was no significant difference in the change in cardiac output between patients receiving ginkgo ("Taponin tablets") and those receiving the control (nifedipine) (P value not reported).
Six studies reported AEs. Two studies indicated that there were no AEs, while four studies reported AEs such as epigastric discomfort, nausea, gastrointestinal reaction, and bitter taste. However, the AEs were not statistically different between the ginkgo and control groups. There were no severe AEs.
The authors acknowledge that the positive findings should not be viewed as definitive. The studies had a risk of bias in design, reporting, and methodology. None of the studies were multicenter, large sample-size RCTs. Also, the studies lacked measurement of a long-term clinical benefit (i.e., measures of cardiac mortality, non-fatal acute myocardial infarction, the need for percutaneous coronary intervention or coronary artery bypass grafting, hospitalization for unstable angina, and frequency of acute angina attacks). It is important to assess the clinical benefit to determine the true impact of ginkgo on AP.
The value of this systematic review is that the Chinese authors evaluated the Chinese literature. Oftentimes, the Chinese literature is excluded from systematic reviews because the authors cannot translate the Chinese language. So, this review is insightful into the studies published in China/Chinese. However, the review would have been more beneficial if the authors would have included more information about the ginkgo products and doses that were evaluated, and whether the statistical data were versus baseline or control. Also, the authors conducted some meta-analyses, but the methods are questionable. It should also be noted that AP is not an indication for ginkgo extracts in accordance with Western herbal drug monographs and pharmacopeias.
—Heather S. Oliff, PhD
