Comprehensive evidence mapping of Chinese medicine for the treatment of pulmonary heart disease: A systematic assessment of efficacy and challenges

Abstract

Background:

This study aims to assess the quality of evidence regarding the use of traditional Chinese medicine (TCM) interventions in pulmonary heart disease (PHD) through a systematic review and meta-analysis of relevant literature.

Methods:

A comprehensive search was performed across both Chinese and English databases, including CNKI, Wanfang, VIP, PubMed, Web of Science, and Cochrane Library, covering studies published up to April 2024. Eligible studies on TCM interventions for cor pulmonale were included. The methodological quality of the studies was evaluated using the AMSTAR 2 tool. An evidence map was constructed to visualize key characteristics such as study population, sample size, and intervention modalities.

Results:

A total of 39 studies were included, comprising systematic reviews, meta-analyses, and network meta-analyses on TCM interventions for PHD. The most common interventions were TCM injections, followed by decoctions and proprietary Chinese medicines. Treatment strategies primarily involved blood activation, tonification, blood stasis resolution, and meridian dredging (Tongluo). The AMSTAR 2 assessments identified several methodological weaknesses, including lack of protocol registration, absence of a list of excluded studies, and insufficient analysis of heterogeneity and risk of bias. According to the evidence map, 36 studies reported beneficial effects and 3 indicated likely benefit, suggesting a potentially positive role of TCM in managing PHD.

Conclusion:

While most studies suggest that TCM interventions may be beneficial for PHD, the overall methodological quality of the evidence is very low. Therefore, the findings should be interpreted with caution. TCM shows promise as a therapeutic option for PHD; however, high-quality systematic reviews are needed to validate these preliminary results.

1. Introduction

Pulmonary heart disease (PHD), also known as cor pulmonale, is a pathological condition characterized by increased pulmonary vascular resistance and elevated pulmonary artery pressure, typically resulting from diseases affecting the bronchi, lung parenchyma, or pulmonary vasculature. These changes lead to the progressive development of pulmonary hypertension, ultimately resulting in right ventricular overload and, in severe cases, right heart failure.^[1,2] Globally, the average prevalence of PHD is estimated at 0.46%, placing a significant physical, emotional, and economic burden on patients, families, and healthcare systems.^[3] The in-hospital mortality rate for patients with PHD is reported to range between 12.5% and 14.5%,^[4] underscoring the urgent need for improved treatment strategies to reduce mortality and enhance patient quality of life.

Currently, conventional Western medical management of PHD primarily focuses on symptomatic relief, including infection control, correction of hypoxia and/or hypercapnia, respiratory support, and treatment of heart failure. These approaches often involve the use of pharmacologic agents such as antitussives, bronchodilators, expectorants, vasodilators, and positive inotropic drugs. While these treatments can offer short-term benefits, their long-term efficacy remains limited.^[5] In contrast, traditional Chinese medicine (TCM) has a long-standing history in the clinical management of PHD. It has demonstrated potential benefits in relieving symptoms, improving patient quality of life, and slowing disease progression.^[6] As such, there is a growing imperative to develop integrated treatment strategies that combine the strengths of both TCM and Western medicine.

Evidence mapping is an emerging research methodology that systematically synthesizes and visually presents existing evidence within a specific field. It provides a comprehensive overview of the landscape, identifies current challenges, and highlights future research directions. Compared to traditional systematic reviews, evidence mapping incorporates a wider range of study types and offers a broader analytical perspective.^[7,8] In recent years, the role of TCM in the treatment of PHD has attracted increasing attention. This study systematically evaluates the available evidence on TCM interventions for PHD and presents the findings through an evidence map, with the aim of supporting the development of clinical practice guidelines, standardization efforts, and future research.

2. Materials and methods

2.1. Literature search

A computer-based search was conducted in major databases, including 3 Chinese databases (China National Knowledge Infrastructure [CNKI], VIP Database for Chinese Technical Periodicals [VIP], Wanfang Database) and 3 English databases (Web of Science, PubMed, Cochrane Library). The search period was set from the inception of the databases until December 15, 2024. The search terms in Chinese were: “Pulmonary Heart Disease,” “Pulmonary Heart Disease,” “Chinese Medicine,” “Proprietary Chinese Medicines,” “Combination of Chinese and Western Medicine,” “Chinese Medicine Injections,” “Meta-analysis,” “Meta-analysis,” “Systematic Evaluation,” “Network Meta-analysis,” “Systematic Review,” and “Systematic Analysis.” The search terms in English were: “Pulmonary Heart Disease,” “Proprietary Chinese Medicines,” “Chinese Medicine Injections,” “Combination of Chinese and Western Medicine,” “Meta-analysis,” “Network Meta-analysis,” “Systematic Evaluation,” “Systematic Review,” and “Systematic Analysis.”

2.2. Inclusion criteria

2.2.1. Study type

Published systematic reviews and meta-analyses worldwide on the treatment of PHD.

2.2.2. Study subjects

Patients diagnosed with PHD, with no restrictions on gender, age, nationality, etc.

2.2.3. Intervention measures

In the included studies, the control groups received either placebo, no treatment (blank control), or standard conventional Western medical treatment, while the intervention groups were treated with TCM alone or in combination with Western medicine.

2.3. Exclusion criteria

Duplicated publications, non-meta-analysis/systematic reviews, non-TCM-related studies, conference abstracts, protocols, reevaluation of systematic reviews, etc.

2.4. Literature screening and data extraction

Literature screening and data extraction were independently performed by 2 researchers, with all results cross-checked for consistency. Any discrepancies were resolved through discussion with a third researcher. Key information from the included studies was extracted using Microsoft Excel, including the article title, first author, publication year, sample size, study population, control intervention, TCM intervention, outcome measures, and specific TCM treatment approaches.

To explore clinical and methodological heterogeneity within the available data, we extracted information from each included systematic review or meta-analysis regarding the type of TCM intervention (e.g., injection or oral formulation), whether it was combined with Western medicine, and the reported stage of PHD. However, as the unit of analysis in this study was the systematic review (rather than individual randomized controlled trials), patient-level and trial-level data were not accessible. Consequently, no formal subgroup analyses or quantitative meta-analyses were conducted.

2.5. Data analysis and presentation

2.5.1. Research conclusions

The results or conclusions of the included studies were classified into 5 types:

1. Beneficial: the intervention showed a statistically significant positive effect (e.g., risk ratio [RR] or odds ratio [OR] significantly different from 1, and 95% CI does not include 1), with at least moderate methodological quality.

2. Possibly beneficial: the results suggested a trend toward benefit, but were not statistically significant (e.g., 95% CI includes 1), or the study quality was low.

3. Harmful: the intervention showed a statistically significant negative effect (e.g., RR < 1 or OR > 1 in an adverse direction), with acceptable quality of evidence.

4. No significant effect: no statistical difference was found between the intervention and control groups (e.g., RR close to 1 with 95% CI including 1).

5. Uncertain: the conclusion could not be clearly drawn due to insufficient information, high heterogeneity, or very low-quality evidence.^[9]

2.5.2. Methodological quality

The methodological quality of all included studies was assessed using the AMSTAR 2 (a measurement tool to assess systematic reviews 2) instrument.^[10] AMSTAR 2 comprises 16 items, each evaluated as “Yes,” “Partially Yes,” or “No.” Among these, items 2, 4, 7, 9, 11, 13, and 15 are designated as critical domains.^[11] Based on the AMSTAR 2 criteria, the overall quality of each study was categorized into 4 levels: high, moderate, low, or critically low. Specifically, studies with no or only one noncritical weakness were rated as high-quality; those with more than one noncritical weakness were rated as moderate quality. If a single critical item was unmet – regardless of the performance on noncritical items – the study was rated as low quality; failure to meet more than one critical item resulted in a critically low rating.^[8]

In addition, we evaluated whether the included systematic reviews reported quantitative assessments of heterogeneity and publication bias. Specifically, we extracted information on the use of the I² statistic for assessing between-study heterogeneity, as well as the use of funnel plots, Begg test, or Egger test for evaluating publication bias. However, many studies either failed to report these analyses in detail or did not apply them appropriately. The absence of standardized assessments for heterogeneity and bias further contributed to the overall low methodological quality ratings.

2.5.3. Evidence map

We used the online evidence mapping tool provided by Pymeta.com to generate a bubble chart that visually represents the key characteristics of the included studies.^[7] In the chart, each bubble corresponds to a single study; the size of the bubble reflects the study’s original sample size, while the color indicates the type of intervention applied. The X-axis displays the study conclusions, categorized into 5 groups: beneficial, possibly beneficial, harmful, no significant effect, and uncertain effect. The Y-axis represents the methodological quality as assessed by AMSTAR 2.^[9]

2.6. Ethical review

This study is based solely on the analysis of previously published literature and does not involve any human participants, identifiable personal data, or patient intervention. Therefore, approval from an ethics committee or institutional review board was not required.

3. Results

3.1. Literature screening

A total of 314 relevant articles were initially retrieved from 6 databases. After removing duplicates, 134 unique records remained. Titles and abstracts were then carefully reviewed, resulting in the exclusion of 42 articles that did not meet the inclusion criteria. Following a more thorough full-text screening, 39 articles were ultimately deemed eligible for inclusion. The detailed literature screening process is illustrated in Figure 1.

Figure 1.

Literature screening process.

3.2. Publication trends of included literature

The overall number of systematic reviews/Meta-analyses related to TCM interventions for PHD shows a fluctuating upward trend, with the highest number of publications in 2021, totaling 12 articles, as shown in Figure 2.

Figure 2.

Annual number of publications on herbal interventions to intervene in pulmonary heart disease.

3.3. Basic characteristics of the included literature

A total of 39 articles were included in this review,^[12–50] of which 32 were published in Chinese^[12–43] and 7 in English.^[44–50] The combined sample size across all studies was 94,205 participants. In all studies, the control groups received conventional Western medicine treatment, while the intervention groups varied as follows: 2 studies used traditional Chinese patent medicines,^[12,32] 5 studies used Chinese herbal decoctions,^{[16,17,20,21,23]} 2 studies employed integrated Chinese and Western medicine approaches,^[22,38] and 30 studies utilized Chinese herbal injections.^{[13–15,18,19,24–31,33–50]}

In terms of therapeutic principles employed in TCM for pulmonary heart disease, 15 studies adopted the “activating blood circulation” method, 12 used the “tonifying and replenishing” approach, 13 applied the “invigorating blood and resolving stasis” method, 5 used the “unblocking meridians” technique, and 14 employed other treatment strategies.

All included studies underwent methodological quality assessment. Specifically, 12 studies were evaluated using the Jadad scale,^{[20,33,35–42,49,50]} 24 studies were assessed using the Cochrane Risk of Bias tool,^{[12–19,21–32,34,43,45,47,48]} and 2 studies utilized a combination of the Jadad scale, Cochrane tool, and GRADE criteria.^[44,46]

Further details of the literature characteristics are provided in Table 1, including study design, population, interventions, and quality appraisal tools. A summary of the key clinical characteristics – such as population demographics, treatment modalities, primary outcome measures, and conclusions – is presented in Table 2.

Table 1.

Basic characteristics of the included literature.

Inclusion of literature	Volume of literature	Sample size	Intervention		Quality evaluation tools
			Treatment group	Control group
W Wu 2024[12]	95	8787	Proprietary Chinese medicines (heart stabilising granules, Tongxinluo Capsules, Qiqi Ginseng Yiqi Drops Pills, Danfei Lung Heart Granules + conventional Western medicine, lung tonic and blood promoting capsules, Astragali Drabanemerosaemerosaemerosaemerosaemerosaetempera strong heart capsules, Musk Heart Preserving Pills) + conventional Western medicine	Conventional Western medicine	Cochrane tools
C Zhang 2024[13]	29	2879	Compound Danshen Injection + Western medicine	Conventional Western medicine	Cochrane tools
J Ban 2024[14]	103	9332	Chinese medicine injections (Shuo Xitong Injection, Chuanxiongzine Injection, Xinwei Long Injection, Danshen Chuanxiongzine Injection, Chuanxiongzine Injection, Senna Mai Injection, Danhong Injection, Ginkgo Damo Injection, Ginseng Dextrose Injection, Ginseng and Forsythia Injection, Tanshinone IIA Sulfonic Acid Sodium Injection, Shuo Xitong Injection) + conventional Western medicines	Conventional Western medicine	Cochrane tools
P Chen 2023[15]	34	2521	Shenfu injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
T Meng 2023[16]	18	1648	Resolving phlegm and activating blood + conventional Western medicine	Conventional Western medicine	Cochrane tools
P Shi 2023[17]	15	1405	Linggui Zhugan decoction + conventional Western medicine	conventional Western medicine	Cochrane tools
M Li 2022[18]	27	2591	Tanshinone II_A sodium sulfonate injection + ACEI	ACEI	Cochrane tools
T Ma 2022[19]	41	3865	Tanshinone II_A sodium sulfonate injection + ACEI	ACEI	Cochrane tools
Mansoor 2022[20]	25	1068	Chinese medicine + conventional western medicine	Conventional Western medicine	Jadad assessment form
X Hou 2022[21]	19	1373	Zhenwu decoction + conventional western medicine	Conventional Western medicine	Cochrane tools
X Feng 2021[22]	11	1072	Combine traditional Chinese and Western medicine	Conventional Western medicine	Cochrane tools
Y You 2021[23]	12	1000	Benefiting qi and activating blood + conventional Western medicine	Conventional Western medicine	Cochrane tools
J Feng 2021[24]	11	960	Xinmai Long injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
C Zheng 2021[25]	19	1469	Sambucus injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
M Jin 2021[26]	21	2151	Danhong injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
G Peng 2021[27]	19	1758	Xinmai Long injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
H Wang 2020[28]	9	876	Shuxue injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
B Xie 2018[29]	21	2005	Danshen Chuanxiongzine injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
J Wu 2018[30]	35	3349	Astragalus injection + conventional Western medicine	conventional Western medicine	Cochrane tools
W Zhang 2017[31]	17	1625	Tanshinone II_A sodium sulfonate injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
Q Dan 2017[32]	6	490	Qishen Yiqi Drops + conventional Western medicine	Conventional Western medicine	Cochrane tools
J Wei 2017[33]	17	1647	Danshen injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
P Zhang 2015[34]	13	1218	Ginkgundamo injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
H Wang 2015[35]	14	1208	Shu Xuning injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
M Luo 2014[36]	17	1429	Danshen Chuanxiongzine injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
H Cao 2013[37]	21	1882	Danhong injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
S Feng 2013[38]	52	4864	Combine traditional Chinese and Western medicine	Conventional Western medicine	Jadad assessment form
G Xu 2013[39]	28	2468	Chuanxiongzine injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
J Li 2012[40]	9	698	Haematoxylin injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
Y Li 2011[41]	8	863	Puerarin injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
J Tao 2011[42]	5	487	Bitter saucer injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form
P Li 2008[43]	11	876	Ginseng injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
HK Shao 2024[44]	19	1739	Tanshinone II_A Sodium Sulfonate Injection + conventional Western medicine	Conventional Western medicine	Jadad assessment form, Cochrane tool, grade criteria
Q Qiu 2020[45]	28	2457	Ginkgundamo injection + conventional Western medicine	Conventional Western medicine	Cochrane tools
KH Wang 2020[46]	118	10,085	Chinese medicine injections (Shuo Xitong Injection, Chuanxiongzine Injection, Xinwei Long Injection, Danshen Chuanxiongzine Injection, Chuanxiongzine Injection, Senna Mai Injection, Danhong Injection, Ginkgo Damo Injection, Ginseng Dextrose Injection, Ginseng and Forsythia Injection, Tanshinone IIA Sulfonic Acid Sodium Injection, Shuo Xitong Injection) + conventional western medicines	Conventional western medicine	Jadad assessment form, Cochrane tool, grade criteria
LW Shi 2015[47]	27	2045	Sambucus injection + Western medicine	Conventional western medicine	Cochrane tools
Y Liu 2014[48]	35	2715	Danhong injection + conventional Western medicine	Conventional western medicine	Cochrane tools
LJ Sheng 2012[49]	34	2683	Chuanxiongzine injection + conventional Western medicine	Conventional western medicine	Jadad assessment form
JS Li 2011[50]	33	2617	Sambucus injection + Western medicine	Conventional western medicine	Jadad assessment form

Table 2.

Classification of basic features.

Categories	Characteristics	Volume of literature
Study population	Chronic pulmonary heart disease	32
	Acute attack of pulmonary heart disease	7
Methods of treatment	Prepared prescription (Chinese medicine)	2
	Decoction (Chinese medicine)	5
	Combine traditional Chinese and Western medicine	2
	Chinese medicine injection	30
Primary outcome indicators (>10 RCTs)	Cardiac function improvement efficiency	19
	Increased LVEF	13
	Increased RVEF	10
	Increase arterial partial PaO2, decrease arterial partial PaCO2	21
	Improvement of erythrocyte pressure	14
	BNP	15
	Adverse reaction	12
Conclusion of the study	Beneficial	36
	Possibly beneficial	3

BNP = brain natriuretic peptide, LVEF = left ventricular ejection fraction, PaCO₂ = pressure of carbon dioxide, PaO₂ = pressure of oxygen, RVEF = right ventricular ejection fraction.

3.4. Methodological quality evaluation

We conducted a methodological quality assessment of the 39 included articles using the AMSTAR 2 tool, which comprises 16 items. The results indicated that the overall quality was rated as moderate in 2 studies, low in 3 studies, and very low in 34 studies. Among the critical domains, 4 studies met the criteria for item 2, 24 for item 4, 2 for item 7, 34 for item 9, all 39 studies met the criteria for item 11, and 23 studies met the criteria for both items 13 and 15. Regarding noncritical items, all 39 studies fully complied with items 1, 3, 5, and 6. Nineteen studies met the criteria for item 8, while 17 studies partially met it. None of the studies fulfilled the requirements for item 10. Items 12 and 14 were satisfied by 28 studies, and item 16 was met by 22 studies. A detailed breakdown of the AMSTAR 2 evaluation is presented in Figure 3 and Table S1 (Supplementary Digital Content, https://links.lww.com/MD/R78).

Figure 3.

AMSTAR 2 scale to evaluate TCM intervention in pulmonary heart disease related literature. AMSTAR 2 = a measurement tool to assess systematic reviews 2, TCM = traditional Chinese medicine.

3.5. Evidence map

Among the 39 included studies, 36 concluded that the interventions were beneficial, while 3 reported them as possibly beneficial. According to the AMSTAR 2 assessment, 2 studies were rated as moderate quality, 3 as low quality, and 34 as very low quality. To more clearly present the distribution of evidence quality and conclusions, categories such as “no obvious effect,” “harmful,” and “uncertain” were omitted from the X-axis, as no studies fell into these groups. Similarly, the Y-axis does not include the “high quality” category, as no studies met this threshold. Further details are provided in Figure 4.

Figure 4.

Evidence mapping for herbal interventions in PHD. PHD = pulmonary heart disease.

Although formal subgroup analysis was not feasible, descriptive categorization revealed that most reviews focused on TCM injection therapies – particularly Salvia miltiorrhiza and Shenmai injections – typically in combination with Western medicine. However, only a few reviews clearly differentiated between the acute and chronic stages of pulmonary heart disease, indicating a lack of specificity and granularity in the current body of evidence.

4. Discussions

In TCM, PHD is not recognized as a distinct diagnostic category. However, based on its predominant clinical manifestations, it is typically classified under syndromes such as lung distention (fei zhang), palpitations (xin ji), and other related patterns. These conditions are generally interpreted within the TCM framework as reflecting a pathogenesis of “root deficiency and branch excess.” Specifically, internal organ dysfunction – particularly of the lung, spleen, and kidney – is viewed as the root deficiency, while pathogenic factors such as blood stasis, phlegm accumulation, fluid retention, and invasion by external pathogens contribute to the excess manifestations.^[12]

The results of this study indicate that the most common TCM interventions for treating PHD are tonification, activating blood circulation, and resolving blood stasis. These TCM intervention categories, though rooted in traditional concepts, also correspond to pharmacological mechanisms increasingly supported by modern research. For instance, “activating blood circulation” therapies often involve herbal ingredients such as Salvia miltiorrhiza or Ligusticum chuanxiong, which have demonstrated antiplatelet aggregation, vasodilatory, and endothelial protective effects. “Tonification” therapies, commonly incorporating Astragalus membranaceus or Panax ginseng, are associated with immunomodulatory, cardiotonic, and antioxidant properties. Interventions aimed at “resolving blood stasis” often contain compounds that enhance microcirculation, reduce blood viscosity, and inhibit thrombosis. While the terminology used in TCM is based on holistic and syndrome differentiation theory, these therapies can also be mapped to biomedical mechanisms such as anti-inflammation, anti-oxidation, regulation of nitric oxide pathways, and improvement of hemodynamics. For clarity, we have provided Table S2 (Supplementary Digital Content, https://links.lww.com/MD/R78) summarizing the key TCM categories and their known pharmacological correlates. Furthermore, the findings suggest that compared to conventional Western medicine treatment, pure TCM or the combination of TCM and Western medicine yields more significant results. Modern pharmacology has found that Chinese medicine can improve heart and lung function through actions such as anti-inflammatory, antioxidant, inhibiting myocardial cell apoptosis, and protecting endothelial function.^[51–54] These studies have promoted the widespread application and development of integrative medicine, and in the future, clinical practices will more fully consider the use of combined TCM and Western medicine interventions for treatment.

This study conducted a methodological quality evaluation of the 39 included studies on TCM interventions for PHD through a systematic review. This in-depth evaluation has provided us with a more comprehensive understanding of the field and has revealed several trends and patterns worthy of attention. The results of our study are presented in the form of an evidence map, a visual approach that allows for a clearer interpretation and understanding of the data. In the map, we have detailed the research conclusions on TCM interventions for PHD, the results of the methodological quality assessment, and the sample sizes of the included studies. These findings not only provide important references for researchers in this field but also offer valuable guidance for the practice of TCM interventions and treatments for PHD.

The 39 articles collected in this study were assessed based on methodological quality evaluation, and the results indicated that most of the studies were of lower quality. Although this study was conducted with at least two independent researchers performing the search, screening, and data extraction in a back-to-back manner, and all elements of PICO (population, intervention, comparison, outcome) were satisfied, several issues remain. First, most studies did not mention the development of a research protocol or prior registration, which could lead to potential biases in the research results. Second, the literature search was not sufficiently comprehensive. In this study, references from the included studies, gray literature, or expert consultations were not included, which may have compromised the systematic and comprehensive nature of the research. Additionally, many studies did not disclose their funding sources, did not sufficiently explore the risk of bias and its potential impact on the results, and did not report potential conflicts of interest, which could decrease the credibility and objectivity of the research findings. Finally, the poor quality of the original literature included in the study is also one of the key reasons for the lower methodological quality. Of the 39 studies ultimately included, only 2 were rated as moderate quality, 3 as low quality, and the remaining 34 were of very low quality. Therefore, future research should strengthen the registration of studies, comprehensive literature searches, discussion of bias risks, and reporting of conflicts of interest to improve the credibility and methodological quality of the studies.

Furthermore, the predominance of very low-quality systematic reviews (34 out of 39) has critical implications for the validity of our synthesized conclusions. These methodological shortcomings – such as unregistered protocols, incomplete literature retrieval, and insufficient assessment of bias – may have introduced systematic errors and reporting biases, thereby inflating the perceived efficacy of TCM interventions. Additionally, the lack of detailed subgroup analyses, transparency in funding sources, and standardized outcome definitions could further distort the evidence landscape. As a result, while our evidence map visually suggests a favorable trend toward TCM efficacy in PHD, the underlying uncertainty must not be overlooked. Readers and policymakers should interpret these findings with caution, and future reviews must prioritize methodological rigor to enhance the reliability of evidence-based decision-making in this field.

At the same time, the limitations of this study and the factors that may influence the results need to be carefully considered. First, we only searched commonly used Chinese and English databases, which may lead to selection bias and, consequently, affect the comprehensive understanding of pulmonary heart disease in this field. Second, we did not fully describe the intervention intensity, duration, or follow-up of TCM treatments, which prevented us from comprehensively monitoring the treatment effects and potential long-term impacts. One notable limitation of our study is the inability to conduct subgroup analyses due to the nature of the included studies. Since we synthesized findings from published systematic reviews rather than primary clinical trials, we lacked access to detailed patient- or trial-level data. Furthermore, because the current study was based on secondary data from existing systematic reviews and meta-analyses, we did not have access to raw outcome data (e.g., effect sizes, standard deviations, confidence intervals) required to perform a re-analysis or generate forest plots. While many of the included studies reported quantitative findings such as ORs and mean differences, their heterogeneity in terms of intervention type, outcome definitions, and comparator arms limited the feasibility of pooling these data in a meaningful way. Therefore, we adopted an evidence mapping approach to visually synthesize the evidence and highlight areas of consistency and gaps. Future overviews or umbrella reviews may consider quantitatively summarizing effect sizes using appropriate statistical models if more homogeneous data are available. As such, heterogeneity across different TCM formulations, disease stages, or treatment settings could not be quantitatively analyzed. We recommend that future systematic reviews report subgroup data more transparently, and that future evidence mapping studies attempt to extract and stratify these features when possible.

In addition to providing an overview of the current evidence, our evidence mapping approach also serves as a strategic tool to guide future research. Through this mapping, we identified that commonly used TCM modalities such as herbal decoctions, Chinese patent medicines, and acupuncture are often supported by systematic reviews of very low methodological quality. This underscores the urgent need to conduct rigorously designed randomized controlled trials targeting these specific interventions, particularly in the context of pulmonary heart disease. Furthermore, the evidence map revealed clusters of studies focusing on similar TCM therapies but lacking consistency in outcome measures and reporting standards. Such fragmentation highlights the necessity for standardized protocols, unified diagnostic criteria, and well-defined endpoints in future trials. By visually clarifying evidence strengths and weaknesses, the map not only supports clinical decision-making but also enables researchers and policymakers to prioritize high-potential TCM therapies for validation through high-quality research.

5. Conclusion

Current evidence suggests that TCM interventions may offer therapeutic benefits for PHD. However, the overall quality of clinical evidence remains low, primarily due to methodological limitations in the existing studies. Therefore, future research should prioritize rigorous study design, standardized outcome measures, and transparent reporting to enhance the reliability and applicability of the findings and to provide stronger evidence for clinical decision-making.

Author contributions

Data curation: Chenyu Zhao, Bangkui Zhang.

Formal analysis: Chenyu Zhao.

Investigation: Jiamei Fu.

Methodology: Bangkui Zhang, Jiamei Fu.

Project administration: Yabin Zhou.

Supervision: Yabin Zhou.

Writing – original draft: Yingyu Wang.

Writing – review & editing: Yingyu Wang.