Effects of traditional Chinese exercises on cardiac rehabilitation in patients with myocardial infarction: a meta-analysis of randomized controlled trials

Objective Traditional Chinese exercises (TCE) are excellent cardiac rehabilitation (CR) training that can effectively improve cardiorespiratory fitness. However, there is no published meta-analysis of TCE on CR in patients with myocardial infarction (MI). Therefore, this study aimed to provide a comprehensive evaluation from multiple perspectives. Methods This meta-analysis is based on the Cochrane Handbook of Systematic Reviews. Eight databases were searched from the date of database construction to March 15, 2023. Two investigators independently screened the literature and assessed their quality. The meta-analysis was performed with RevMan5.4 software. Results A total of 21 articles involving 1,890 patients were included. N-terminal pro-brain natriuretic peptide (NT-proBNP) in the TCE group were lower than the control group (MD = −96.34, 95%CI: −140.69 ∼−51.98, P < 0.00001, I2 = 96%), the left ventricular ejection fraction (LVEF) in the TCE group was higher than the control group (MD = 4.58, 95%CI: 3.28–5.88, P < 0.00001, I2 = 79%), the left ventricular end diastolic dimension (LVDD) in TCE group was lower than the control group (MD = −3.83, 95%CI: −5.27 ∼−2.38, P < 0.00001, I2 = 94%), the left ventricular end systolic diameter (LVESD) in TCE group was lower than the control group (MD = −2.17, 95%CI: −4.10 ∼−0.24, P < 0.00001, I2 = 96%), The 6-minute walk test (6MWT) in the TCE group was higher than the control group (MD = 69.60, 95%CI: 34.59–104.60, P < 0.00001, I2 = 99%), the oxygen uptake (VO2) in the TCE group was higher than the control group (MD = 4.38, 95%CI: 2.25–6.51, P < 0.00001, I2 = 94%), the 36-item short form survey (SF-36) in the TCE group was higher than the control group (MD = 13.34, 95%CI: 9.25–17.42, P = 0.008, I2 = 75%), the Hamilton Anxiety Scale (HAMA) in the TCE group was lower than the control group (MD = −4.34, 95%CI: −5.18 ∼−3.50, P = 1.00, I2 = 0%), the Hamilton Depression Scale (HAMD) in the TCE group was lower than the control group (MD = −3.48, 95%CI: −5.35 ∼−1.61, P = 0.0002, I2 = 88%), the incidence of major adverse cardiac events (MACEs) in the TCE group was lower than the control group (RR = 0.31, 95%CI: 0.20–0.47, P = 0.52, I2 = 0%). Subgroup analysis revealed differences in TCE types could be a potential source of heterogeneity. Conclusion MI patients who used TCE have not only notable improvements in cardiopulmonary function, physical function, quality of life, and emotions but also reduced the incidence of MACEs. Tai Chi might be more efficient than Ba Duan Jin. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023408675.


Introduction
Cardiovascular disease (CVD) accounts for a large proportion of a range of non-communicable diseases.Acute myocardial infarction (AMI), one of the primary causes of death from coronary heart disease (CHD) (1), affects approximately 11.39 million individuals in China, where the prevalence of CVD is continually rising (2).The usual treatment for AMI often involves percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG), which can enhance the quality of life for myocardial infarction (MI) patients by restoring perfusion.However, how to recover the pre-morbid health status remains an urgent public health issue (2).Cardiac rehabilitation (CR) is a comprehensive multidisciplinary program specifically designed for patients with CVD.The main objectives are to increase daily function and lessen cardiovascular risk factors (3).The European Society of Cardiology, American Heart Association, and American College of Cardiology all suggest utilizing CR as a Class I standard of care following an AMI (4).
Traditional Chinese Exercise (TCE) is a type of therapeutic, aerobic, mind-body exercise that has a history dating back over 3,000 years from traditional Chinese medicine (5).TCE mainly includes Tai Chi, Ba Duan Jin, Qi Gong, Yi Jin Jing, Wu Qin Xi, and other low to medium-intensity exercises (6).As a mild musclestrengthening sport, TCE combines spiritual meditation with moderate postures, musculoskeletal stretching, and deep breathing (7,8).It has been shown in numerous studies to be an effective exercise for CR and to enhance cardiorespiratory health (9,10).
Early and appropriate CR not only improves cardiac function and quality of life but also prognosis in MI patients.However, there is no published meta-analysis evaluating the effect of TCE in these patients.Accordingly, the purpose of this study is to systematically evaluate the effects from multiple perspectives and provide a resource for future clinical advice.

Materials and methods
The Cochrane Handbook of Systematic Reviews served as the foundation for our meta-analysis.The results of this study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.This meta-analysis has been registered in PROSPERO (registration number: CRD42023408675).
Exclusion criteria: (1) Duplicate literature.(2) Animal experiments, meta-analyses, and systematic reviews.(3) Studies with insufficient data, such as those in which the data could not be combined with other outcome indicators.reporting, and other biases.Each entry was evaluated for one of low risk, high risk, and unclear risk.

Statistical analysis
The meta-analysis was performed with the RevMan5.4 software.Dichotomous variables were expressed as relative risk (RR) and 95% confidence interval (CI), and continuous variables were expressed as mean difference (MD) and 95% CI.I 2 was used to determine the heterogeneity.Meta-analysis was conducted using the fixed-effects model if P > 0.1 and I 2 < 50%.Meta-analysis was conducted using the random-effects model if P ≤ 0.1 and I 2 ≥ 50%.Sensitivity analysis and subgroup analysis were used to examine the source of heterogeneity.The publication bias was displayed in a funnel plot.The test level of the meta-analysis was set as α = 0.05.

Search results and population characteristics
The study screening process is illustrated in Figure 1.A total of 258 articles were searched through the databases (21 from Pubmed, 28 from Web of Science, 20 from Embase, 29 from Cochrane Library, 48 from CNKI, 33 from Wan Fang, 49 from VIP, and 30 from Sinomed).After removing duplicates and screening, 21 articles revolving 1,890 patients were eligible for meta-analysis.The general characteristics are summarized in Table 1.According to the table, 17 studies were from China and one was from Brazil.
Interventions included Ba Duan Jin, Tai Chi Quan, and Tai Chi Ball.Intervention duration ranged from two weeks to one year.

Quality assessment
The results of the risk of bias evaluation of the included literature are presented in Supplementary Table S1.Two studies (12, 28) employed random samplings, 16 studies utilized random number table grouping and three studies (24)(25)(26) did not describe the randomization method.Only Rosane (32) used blinding of outcome assessment.

Meta analysis 3.3.1. Effects of TCE on Nt-proBNP
Seven articles involving 514 patients reported NT-proBNP levels.The NT-proBNP of patients who engaged in TCE was significantly less compared with the control group based on a random-effects model (MD = −96.34,95%CI: −140.69-−51.98,P < 0.00001, I 2 = 96%) (Figure 2).Eight studies involving 786 patients reported the LVDD outcome.The LVDD of patients who engaged in TCE was significantly less Four studies involving 456 patients reported the LVESD outcome.The LVESD of patients who engaged in TCE was significantly less compared with the control group based on a random-effects model (MD = −2.17,95%CI: −4.10-−0.24,P < 0.00001, I 2 = 96%) (Figure 3C).

Effects of TCE on physical function
Ten studies involving 915 patients reported the 6MWT outcome.The 6MWT of patients who engaged in TCE was significantly improved compared with the control group based on a random-effects model (MD = 69.60,95%CI: 34.59-104.60,P < 0.00001, I 2 = 99%) (Figure 4A).
Five studies involving 448 patients reported the VO 2 outcome.The VO 2 of patients who engaged in TCE was significantly improved compared with the control group based on a random-effects model (MD = 4.38, 95%CI: 2.25-6.51,P < 0.00001, I = 94%) (Figure 4B).

Effects of TCE on quality of life
Four studies involving 372 patients estimated the quality of life with SF-36 outcome.The SF-36 score of patients who engaged in   The forest plot of NT-proBNP.

Effects of TCE on emotional distress
Two studies involving 120 patients reported the HAMA outcome.The HAMA of patients who engaged in TCE was significantly less compared with the control group based on a fixed-effects model (MD = −4.34,95%CI: −5.18-−3.50,P = 1.00,I 2 = 0%) (Figure 6A).

Effects of TCE on MCAEs
Five articles involving 526 patients reported the MACEs outcome.The incidence of MACEs of patients who engaged in TCE was significantly less compared with the control group based on a fixed-effects model (RR = 0.31, 95%CI: 0.20-0.47,P = 0.52, I 2 = 0%) (Figure 7).

Sensitivity analysis and subgroup analysis
Sensitivity analyses were performed by excluding each study one by one.The results revealed NT-proBNP, LVEF, LVDD, LVESD, 6MWT, and VO 2 outcomes were not significantly altered.The sensitivity of the SF-36 outcome decreased when Zhang's study (24) was removed (I 2 changed to 50%), and the sensitivity of the HAMD outcome decreased when Guo's study (20) was excluded (I 2 changed to 0%).
Meanwhile, we implemented subgroup analyses of NT-proBNP, LVEF, 6MWT, VO 2 , and SF-36 outcomes according to the type of TCE in Table 2.There are three subgroups depending on the type of exercise: Tai Chi, Ba Duan Jin, and Tai The forest plots of (A) LVEF, (B) LVDD, (C) LVESD.The forest plots of (A) 6MWT, (B) VO 2.

FIGURE 5
The forest plot of SF-36.

Publication bias
Funnel plots were used to assess the publication bias of the 21 included articles.We drew a funnel plot with the LVEF outcome divided into three subgroups as an example.As seen in Figure 8, all studies were relatively evenly distributed and located on both sides of the axis, and the bias was acceptable.

Discussion
MI is a high-incidence disease worldwide, bringing a heavy social burden, especially for low and middle-income countries (33).Numerous studies have indicated that PCI only solves the blockage problem of blood vessels, but long-term rehabilitation exercises are still needed to restore myocardial function (34,35).The common belief among patients is that after a MI, exercise should be avoided.However, patients who have undergone PCI or CABG should participate in a clinically supervised exercise program.According to Fernandez's study (36), patients who engage in CR have a 26% reduction in mortality and an 18% reduction in hospital readmission rates compared to patients who do not participate in CR.Exercises for post-MI rehabilitation are a crucial part of enhancing patients' quality of well-being and long-term prognosis following drug and surgical treatment.Additionally, it plays a key role in cardiac remodeling and cardiovascular regulation (37).Although CR is strongly recommended as a post-MI treatment, the current underuse is concerning (38,39).Thus, our meta-analysis focused on MI patients.In recent years, TCEs such as Tai Chi, Qi Gong, and Ba Duan Jin have become increasingly popular around the world because of their gentle movements, low-risk, easy training, ancd long-term adherence.The forest plot of MCAEs.TCE is not only effective in regulating the physical condition and mental health of patients with Parkinson's disease, type 2 diabetes, chronic obstructive pulmonary disease, chronic pain disorders, and cancer but also beneficial in improving the cardiopulmonary function and quality of life (7).A total of 21 RCTs comprising 1,890 patients were included for the first time to perform the meta-analysis.Unfortunately, Tai Chi and Ba Duan Jin were the only TCEs included.In comparison to the control group, patients in the TCE group demonstrated better results in NT-proBNP, LVEF, LVDD, LVESD, 6MWT, VO 2 , SF-36 scores, HAMA, and HAMD scale outcomes, and showed a decrease in the MACEs outcome.In addition, Ba Duan Jin and Tai Chi were likewise discovered to be safe, with no instances of TCE-related adverse events.This is consistent with Ting Liu's meta-analysis, Tai Chi increases social well-being and physical endurance in CHD patients (40).A randomized controlled trial reported that adapted personalized motor activity could improve health in individuals with mental disorders and physical comorbidities (41).Notably, our study further demonstrated that TCE improved the emotions of patients with MI as well.About 50% of patients experience anxiety after MI (42).Due to diminished cardiopulmonary function, which affects their capacity for employment and social contact as well as their long-term drug dependence, frequent hospitalizations, and significant financial stress, they are more prone to anxiety, depression, and other negative emotions.Therefore, TCE is very suitable and effective for MI patients to improve their mental and physical function.Apart from that, some researchers believed that TCE might influence cholesterol (18) and myocardial fibrosis levels (23) throughout the screening.However, the number of studies was not enough to perform a meta-analysis.
Furthermore, we conducted sensitivity analysis and subgroup analysis to investigate the source of heterogeneity.Except for HAMA and MACEs outcomes, some heterogeneity in the results of other outcomes may be due to certain clinical and methodological variations in different trials.Subgroup analysis revealed differences in TCE types as a potential source of heterogeneity and suggested that Tai Chi might be more efficient than Ba Duan Jin.
TCE involves the purposeful regulation of breath and thought, in harmony with the control of the body.Combining self-awareness with physical posture, the flow of breath, and stillness of thought is considered an exercise that activates the natural self-regulatory capacity to stimulate a balanced release of endogenous neurohormones (43).Overall, our meta-analysis provided reliable results in terms of TCE improving CR in patients with MI.

Limitations
This study has several limitations.Firstly, there is a lack of gray literature.If the findings from unpublished studies differ from the published data, the meta-analysis may become biased.Secondly, most of the included literature did not explicitly mention allocation concealment and only one study was blinded, so selection bias may be present.Finally, only Ba Duan Jin and Tai Chi were discussed in this essay.The majority of the included RCTs were Chinese, so language restrictions might lead to publication bias.

Conclusion
In conclusion, the use of TCE in MI patients showed significant improvements in cardiac function, physical function, quality of life, and mental health, also reduced the incidence of MACEs, which has good clinical application value and is recommended as a complementary therapy for CR in MI patients.It was found that Tai Chi might be more efficient than Ba Duan Jin.However, the above findings still need to be verified by more high-quality RCTs.The specific frequency and duration of different exercises should be analyzed to prescribe the most appropriate exercise prescription in the future.

FIGURE 1 Flow
FIGURE 1Flow chart of the search strategy.

TABLE 1
Characteristics of the clinical trials included in the meta-analysis.

TABLE 2
Subgroup analyses.Funnel plot of LVEF.