Effects of meditation on health promoting protective factors of persons with cardiovascular disease—a quasi-experimental pilot study with pre-post comparison

Introduction

Cardiovascular diseases are a group of diseases that affect the heart and blood vessels. These are diseases that arise due to atherosclerosis and can have an acute or chronic course. These include, for example, arterial hypertension, coronary heart disease, myocardial infarction, or apoplexy (1,2). There is great potential for health promotion to be integrated into multimodal care or treatment of cardiovascular diseases Especially in the psychosocial dimensions, evidence-based measures can be implemented at the structural and behavioural level, which ultimately promote health and contribute to the prevention of cardiovascular diseases or, in the case of already existing cardiovascular diseases, improve the quality of life and support coping with the disease.

However, there are only few relevant studies to date that have investigated the effects of interventions specifically for people with cardiovascular diseases on a health-promoting and psychosocial level. For this reason, an explorative controlled intervention study was carried out in the context of this survey, which examined the possible effectiveness of meditation on the strengthening of health-promoting personal competencies in persons with cardiovascular diseases in a before-and-after comparison using the main parameters of sense of coherence, resilience, and self-compassion.

The interconnections and interrelationships, so-called mind-body interactions, between brain, mind, body, behaviour at the individual level as well as the social dimensions and determinants play a decisive role in health and mortality (3,4). Psychosocial aspects in particular seem to have a significant influence on the entire progression of a disease. But even in the case of already existing health restrictions or illnesses, psychological factors influence the prognostic progression (5). In the meantime, these connections have also been recognised in cardiology and a new discipline of psychocardiology is being established (6). There are already guidelines with therapy options in psychocardiology (7), which, however, have so far insufficiently found their way into practice. In addition, therapeutic care—also due to a lack of specialists and time—can neither be guaranteed adequately nor comprehensively (6,8). Lifestyle factors and above all stress play a decisive role in the development and progression of cardiovascular diseases.

Stress and various diseases are mutually dependent in this context. Many diseases, such as cancer, chronic pain or depression, are themselves stressors, on the other hand, chronic stress can lead to a variety of different diseases on a physical and/or psychological level (9-12). The triggering of stress as well as the subjective experience of stress and the strength of the stress perception are individual and often depend on life history, upbringing, experience, and imprinting. In connection with this, the way people deal with stress and their ability to cope with stress, so-called coping (11,13), are also individually distinct. Because heart and brain are in constant exchange, stress sensation and stress reactions also affect the heart (14,15). The activation of the sympathetic nervous system because of an acute stress reaction has a direct effect on the cardiovascular system with an increase in heart and respiratory frequency, blood pressure and vasoconstriction of the blood vessels.

If permanent overload and prolonged exposure to stressors lead to a chronicity of stress, the human body can only adapt to a certain degree. As soon as the body can no longer recover and regulate to its normal level due to constantly excessive activation caused by stress, this permanent strain can lead to long-term damage, which can sometimes be severe (9,16,17). If the stress limit is permanently exceeded and a return to a physiological relaxation phase is no longer possible, physical and/or psychological illnesses can be triggered (3,9,18,19). In addition, over the course of the chronification process, the increased and constant release of cortisol leads to permanently elevated cortisol levels. This also inhibits the immune system, as the formation of lymphocytes and antibodies is hindered. This in turn can lead to other secondary diseases (5,20).

Strengthening health-promoting competencies through meditation

The health-promoting personal competencies—and thus also sense of coherence, resilience, and self-compassion—can be learned throughout the entire lifespan and can be strengthened in a targeted manner (21-23). Various mind-body techniques such as Yoga, Tai Chi, Pilates and various meditation techniques are available for this purpose, which focus on the principle of mindfulness (24).

As early as 2017, in a scientific statement on meditation and cardiovascular risk the American Heart Association (AHA) pointed out that meditation could be considered as an additional guideline-based intervention to reduce the risk of cardiovascular disease (25).

Current state of research

In a scientific statement by the AHA, Levine et al. (26) stated that, even if the studies on meditation indicate a possible benefit for cardiovascular risk, the quality and in some cases also the quantity of the study data is modest. There are no studies on the possible effects of Metta meditation on cardiovascular disease. Likewise, there are no studies to date that have investigated possible effects of Metta meditation on health-promoting personal competencies or protective factors or explicitly on sense of coherence.

Objective

As a result of the previous considerations, a research gap was identified regarding the evidence of the possible effects of Metta meditation on health-promoting personal competencies in people with cardiovascular disease.

The aim of the research project is to investigate possible effects on health-promoting personal competencies—explicitly on sense of coherence, resilience, and self-compassion—in people with cardiovascular disease through the practice of Metta meditation. We present this article in accordance with the TREND reporting checklist (available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-74/rc).

Methods

Study design

To demonstrate the potential impact of health-related interventions, a controlled non-randomised longitudinal pilot intervention study was chosen as study design (27-30).

After the first survey with both groups [t₀/measurement time (MT)1], the intervention group (IG) started the 12-week Metta meditation programme, which took place online once a week for about 45 minutes. After the 12 weeks, both groups were surveyed again (t₁/MT2).

The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the institutional ethics committee of University of Applied Sciences Coburg (No. HC-Kohls-Weiß-20220708) and informed consent was obtained from all individual participants.

Acquisition of study participants

Between September 2022 and January 2023, about 335 people were personally informed and invited to participate in the intervention on the cardiology units of the REGIOMED Hospital Coburg. Out of 335 people, 42 people agreed to be contacted and to receive further information about the research project and the offer to participate in a cost-free Metta meditation course. After a first contact with the 40 persons, seven actively communicated their refusal. The information letter on participation in the study was then sent to 33 people, 15 of whom signed and returned the consent form. While 14 people participated in the first interview, nine attended the first intervention unit. The number of participants in the 12 individual meditation sessions varied between four (min) and 11 (max) and averaged six and a half participants per session [mean (M) =6.5].

The people for the control group (CG) were recruited in Germany, Austria, and the German-speaking part of Switzerland by contacting and publishing them with or forwarding them to participants, self-help group contact points of the federal states and self-help groups as well as cardiac sports groups. The study participants were also recruited via the social networks Facebook and LinkedIn as well as the research platform SurveyCircle.

This reached 119 people who considered participating and accessed the online questionnaire.

Data collection tools

The following quantitative measurement instruments were used for both MTs: the Minnesota Living with Heart Failure^® Questionnaire (MLHFQ) (31), the 13-item Sense of Coherence Scale (SOC-13) (32), the Resilience Scale (33), the Self-Compassion Scale short form (SCS-sf) German version (34,35), the German version of the 10-item Perceived Stress Scale (PSS-10) (36), the Stress Coping subscale of the Stress and Coping Inventory (SCI) (37), and the blood pressure parameters of the study participants, which had been measured and documented under their own responsibility.

In addition, relevant socio-demographic data as well as some parameters in the IG were asked for the second MT. The data was collected using the online survey tool QuestorPro.

Intervention implementation

The intervention consisted of a 12-week Metta meditation course held online once a week for about 45 minutes. The meditation course was led by a relaxation trainer. Due to the coronavirus disease 2019 (COVID-19) pandemic, this was conducted online via video conference (Zoom). After a brief discussion and short presentation on the topics of heart disease, stress and meditation, the meditation was practised under verbal guidance. After the meditation session, the participants were offered space for further discussion. As with the structure of Metta meditation, the practice of meditation was gradual over the first 6 weeks. The instructions for meditation were compiled according to Haubold (38), Henkelmann (39), and Känner (40). At the end of the course, recorded audio files of the meditation instructions were made available for the participants to download.

The loving-kindness meditation (LKM), also called Metta meditation, is a widely practised form of meditation.

The special feature of Metta meditation—or LKM—is the all-encompassing love that is at the centre of the meditation practice. Metta meditation is a form of mindfulness meditation and is also well suited for beginners to meditation practice. The positive effects of Metta meditation include accepting stressful emotions and transforming them into an accepting attitude, as well as adopting a benevolent attitude towards oneself and all living beings (40).

For Metta meditation, there are already some studies that prove the effects of this form of meditation on different parameters (41-46).

Statistical analyses

Statistical analyses were performed using IBM^® SSPS^® Statistics software (version 29.0.0.0). Due to the exploratory nature of the study, the significance level was set at P<0.05 and the confidence interval (CI) at 95%.

First, the data collected at t₀ and t₁ were analysed descriptively and statistically. Then, all relevant variables were tested for normal distribution using the Kolmogorov-Smirnov test (sample size <50). Inferential statistical procedures were then applied to calculate possible statistically significant results for the pre-post and group comparison. For this purpose, analyses of variance (ANOVAs) with repeated measures were carried out to determine significant differences. For the case of multiple testing, the α-error was corrected according to Bonferroni (47).

Results

All results were calculated based on the data set that had been compiled by processing the raw data using data set cleaning, mean imputation, or exclusion of data and post-hoc reclassification of variables.

It should be noted that due to the sample size, all results have only an explorative non-representative character. This is also shown by a post-hoc power analysis.

Dropout rate

The dropout rate between the number of people invited to participate in the intervention and the number of participants in the first intervention session was 97%. Within the IG, the dropout rate between the number of people who gave consent to be contacted and the number of participants who attended the first intervention session was 79%. The dropout rate between the sample size at MT1 and MT2 of the IG was 31%.

Between the preliminary and final CG sample sizes, the dropout rate was 40%.

Characteristics of the sample

The socio-demographic characteristics of the sample were collected at the first measurement point. The total sample (n=29) consisted of 31% female and 69% male participants. The median age of all respondents was 63 years [M =61.66; standard deviation (SD) =14.072] with a range of 57 years (min–max, 30–87 years). Of the total sample, 3.4% named hypertension as the central diagnosis, 6.9% peripheral arterial occlusive disease, 6.9% entered details in the box other and listed aneurysm surgery with subsequent Dressler’s syndrome, Tako-Tsubo syndrome, and vitiation as well as heart failure and arrhythmia (defibrillator), each 10.3% named a heart attack or chronic heart failure, 17.2% a heart valve insufficiency, 20.7% named coronary heart disease as the central diagnosis and 24.1% cardiac arrhythmias.

ANOVAs

To answer the scientific question on significant differences, several repeated-measures ANOVAs were conducted. All Mauchly tests for sphericity were not significant, so that the ANOVAs were allowed to be carried out.

There were no significant differences in the parameters of sense of coherence, resilience, self-compassion, and in blood pressure parameters in the pre-post comparison within the respective groups nor between the two groups.

A repeated-measures ANOVA showed that there were significant differences within the groups {F[1, 27] =4.590, P=0.041, η_p²=0.145, n=29} regarding the frequency of rehospitalisation in the pre-post comparison, which corresponded to a strong effect according to Cohen (Cohen’s f=0.412). There were also significant differences between the two groups when the MT was taken into account as well as without considering the MT. Therefore, there were significant differences in the frequency of rehospitalisation in the pre-post comparison within the respective groups and between both groups.

Exploratory analyses

During the evaluation process, non-hypothesis-driven but relevant results also emerged, which are reported below.

A repeated-measures ANOVA showed that the health-related quality of life in the pre-post comparison differed significantly within the individuals of both groups {F[1, 26] =11.697, P=0.03, η_p²=0.310, n=28}. According to Cohen, this corresponded to a strong effect (Cohen’s f=0.670).

Significant differences were also found in the emotional and physical dimensions of health-related quality of life within both groups.

Furthermore, another ANOVA with repeated measures for perceived stress level showed a significant difference in the pre-post comparison both within the groups {F[1, 27] =5.421, P=0.03, η_p²=0.167, n=29}, which corresponded to a strong effect according to Cohen (Cohen’s f=0.448), as well as between both groups taking into account the MT {F[1, 27] =4.351, P=0.047, η_p²=0.139, n=29}, which also corresponded to a strong effect (Cohen’s f=0.402) according to Cohen.

In addition, there was a significant difference in the subscale helplessness within both groups.

Finally, a repeated-measures ANOVA for the Stress Coping subscale of the SCI showed that the total score differed significantly from each other in the pre-post comparison within the individuals of both groups {F[1, 26] =6.790, P=0.02, η_p²=0.207, n=28}. According to Cohen, this corresponded to a strong effect (Cohen’s f=0.511). Neither taking into account the MT nor not taking into account the MT showed significant group differences in the before-after comparison. For the coping strategies positive thinking {F[1, 26] =9.951, P=0.004, η_p²=0.207, n=28}, which corresponded to a strong effect according to Cohen (Cohen’s f=0.619), and social support {F[1, 26] =4.343, P=0.047, η_p²=0.143, n=28}, which was a medium effect according to Cohen (Cohen’s f=0.408), showed significant pre-post differences within individuals of both groups. The differences when MT was taken into account were not significant. No significant differences were found in the pre-post comparison for the coping strategies. Active stress coping, keeping faith as well as alcohol and cigarette consumption.

Discussion

Strengths and limitations

Since small sample sizes normally lead to low statistical power, a higher probability of α-error as well as β-error can be assumed, i.e., a small number of data can pretend the effectiveness of interventions.

It should therefore be noted that statistically significant results (significance level P<0.05) can only be regarded as explorative because of the small sample. Furthermore, and due to this, the statistical power is only insufficient, which was confirmed by a post-hoc power analysis.

In addition, the participants were assigned to the two groups without randomisation.

Furthermore, no follow-up survey was conducted that would allow conclusions to be drawn about possible long-term effects and effects that were not yet fully developed at the time of data collection at the second measurement point.

Additionally, it should be noted that because of to the online recruitment of the CG participants, there was no personal interaction with them and no personal assessment could be made. For the persons who gave their consent to participate in the intervention, a personal affinity for meditation could have been decisive. Overall, no external validity is given due to the sample selection, sample size, and sample composition.

Moreover, the possibility of some distortions in the response behaviour (response bias) of the study participants should be pointed out.

Finally, there are always systematic confounders that can be person-, condition-, or situation-related and are not controlled, such as participant characteristics or external factors (47).

Through the exclusive use of validated questionnaires, the quality criteria of objectivity, reliability and internal validity are fulfilled regarding the measurement instruments.

Finally, the inclusion of a CG also contributes to a higher internal validity of this study. During the implementation of the intervention, the general conditions were maintained as well as possible to control for possible confounders. Finally, this intervention study represents a benefit especially for the persons with cardiovascular diseases.

Key findings

One of the main findings of this study is that a significant reduction in stress was measurable in the IG. Furthermore, there was a significant improvement in stress coping skills in the IG.

Finally, a significant difference was indicated regarding the frequency of rehospitalisation of participants of the IG in the pre-post comparison.

Comparison with similar research

It should be noted that the research hypothesis was investigated for the first time in the context of this pilot study. Due to this, the classification in the existing state of research proves to be difficult.

First, it should be noted that within this pilot study, the practice of Metta meditation in people with cardiovascular disease did not strengthen the health-promoting personal competencies sense of coherence, resilience, and self-compassion. This was also shown for the parameters resilience and self-compassion in an RCT by Pidgeon et al. (48) After an intervention with Metta meditation, no significant differences were found between the IG and CG with regard to the variables resilience, self-compassion and mindfulness. Only after 4 months a strengthening of resilience could be measured. A meta-analysis by Reilly and Stuyvenberg (49), on the other hand, proved the effectiveness of Metta meditation in strengthening self-compassion. To date, there are no studies on a possible effect of Metta meditation on sense of coherence. It is therefore possible that the variables of sense of coherence, resilience and self-compassion can only be determined after a longer period of meditation practice and/or only in follow-up measurements.

Only the hypothesis that the practice of Metta meditation significantly reduces the number of rehospitalizations could be confirmed {MT: F[1, 27] =4.590, P=0.041, f=0.412; MT × group: F[1, 27] =5.607, P=0.03, f=0.456; group: F[1, 27] =11.129, P=0.002, f=0.642}.

However, the explorative analyses revealed significant pre-post differences in stress perception {MT: F[1, 27] =5.421, P=0.03, f=0.448; MT × group: F[1, 27] =4.351, P=0.047, f=0.402}, which corresponded to a strong effect and could be attributed to the individuals in the IG (t₀: IG: M =26.33 with SD =6.93; CG: M =26.45 with SD =8.71; t₁: IG: M =21.78 with SD =5.78; CG: M =26.20 with SD =7.05). This was accompanied by a significant improvement in coping strategies in the IG at the second MT, corresponding to a strong effect {F[1, 26] =6.790, P=0.02, f=0.511}. With regard to health-related quality of life, it was noticeable that the values improved significantly in the before-after comparison {MT: F[1, 26] =11.697, P=0.002, f=0.670} and showed a strong effect. The quality of life in both groups was already significantly better than that of the comparison sample at the first MT. Surprisingly, however, the change in the pre-post comparison was evident in both groups (t₀: IG: M =35.11 with SD =28.55; CG: M =30.74 with SD =18.52; t₁: IG: M =23.22 with SD =25.45; CG: M =24.95 with SD =18.26).

Explanations of findings

Thus, the practice of Metta meditation in people with cardiovascular disease is likely to have reduced the perceived stress load and strengthened the health-promoting personal competencies regarding stress management strategies. However, it cannot be conclusively assessed whether the significant change in health-related quality of life in the IG was also caused by the practice of Metta meditation or by other disturbance effects, as this also occurred in the CG. A so-called spring effect (50,51) could possibly explain the improvement in quality of life and especially in the emotional dimension of quality of life in both groups.

It is also possible, referring to chapter 1—health-promoting personal competencies, that there is a directed connection between the protective factor of stress management and the other health-promoting personal competencies sense of coherence, resilience, and self-compassion. It is conceivable, for example, that the reduction of stress and the strengthening of coping strategies are prerequisites for a stronger development of sense of coherence, resilience, and self-compassion. Only when the physiological stress reaction is gradually restored and the cortisol level and the function of the immune system are normalised, there could be a basis for the body to carry out other processes of change in its entirety—such as strengthening health-promoting personal protective factors.

Conclusions

Implications and actions needed

However, only based on the results of several large-scale studies can verifiable conclusions be drawn about a strengthening of health-promoting personal protective factors in people with cardiovascular diseases through the practice of Metta meditation, and possible correlations be recognised. Follow-up surveys are also mandatory for this.

Due to the complex interrelationships outlined above, interdisciplinary multimodal treatment approaches for cardiovascular diseases are absolutely indicated. Socio-economic and psychosocial factors should already be assessed during the diagnostic phase and psychological tests should be carried out to be able to make recommendations for individually specific interventions. In addition to imparting knowledge and recommendations on exercise and dietary behaviour, these should above all include measures for coping with stress, promoting motivation and learning relaxation techniques. In principle, patient-centred, participatory communication should be aimed for (52). However, such health-promoting and (secondary) preventive offers are not available nationwide and are hardly or not at all accessible, especially for patients in rural areas (53). The results of surveys on the health care situation, which were carried out primarily among adults with congenital heart defects, unanimously show major deficits, especially in general and family doctor care (54-56). An exploratory analysis of needs and requirements on the care structure of specific health-promoting services for adults with congenital heart defects in Germany showed that counselling on health-promoting services received an average grade of still sufficient 4.4 (M =4.41, SD =1.404, n=74). Furthermore, 75.6% (n=86) were not aware of any such health-promoting services specifically for adults with congenital heart defects (57). However, health promotion is an element that should not be neglected, as it makes a decisive contribution to creating, increasing, maintaining and restoring quality of life and well-being. Due to the salutogenetic approach, the focus here is primarily on strengthening health and personal resources, which are to be distinguished as personal protective factors from risk factors (58).

Furthermore, it is indispensable to create low-threshold and barrier-free health promoting offers for people with cardiovascular disease, especially for those with congenital heart defects. Because the number of adults with congenital heart defects is steadily increasing, while the care situation is not improving fast enough. A holistic treatment approach is urgently needed, especially with regard to the psychological stress situations of these patients (57,59,60).

Acknowledgments

We thank all participants for their support. Parts of the present study were submitted by K.W. as a master’s thesis as part of the health promotion course at Coburg University of Applied Sciences, which was supervised by N.K. After grading, the manuscript of the present study was prepared based on the data collected during the master’s thesis.

Funding: None.

Footnote

Peer Review and Provenance: This article was commissioned by the Guest Editor (Harald Kaemmerer) for the series “Current Management Aspects in Adult Congenital Heart Disease (ACHD): Part VI” published in Cardiovascular Diagnosis and Therapy. The article has undergone external peer review.

Reporting Checklist: The authors completed the TREND reporting checklist. Available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-74/rc

Data Sharing Statement: Available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-74/dss

Peer Review File: Available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-74/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://cdt.amegroups.com/article/view/10.21037/cdt-24-74/coif). The series “Current Management Aspects in Adult Congenital Heart Disease (ACHD): Part VI” was commissioned by the editorial office without any funding or sponsorship. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). The study was approved by the institutional ethics committee of University of Applied Sciences Coburg (No. HC-Kohls-Weiß-20220708) and informed consent was obtained from all individual participants.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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