1. Introduction
Because of social and industrial changes, the patterns of many diseases have changed. Today, chronic illnesses, including cardiovascular ones, have become the most important health and psychological problems in societies. Cardiovascular specialists have often referred to biological agents as causing heart diseases, but it has recently been found that psychological factors are both contributing to and exacerbating heart diseases [3].
Cognitive emotion regulation strategies are among the factors that can affect heart diseases. Dialectical behavior therapy is an innovation in psychological treatment. It is one of the critical skills acquired in this type of emotion regulation therapy [12].
The main question of this study is whether emotion regulation training based on dialectical behavior therapy can affect cognitive emotion regulation and quality of life in patients with cardiac problems.

2. Materials and Methods
This study is quasi-experimental research with a pretest-posttest and control group. The statistical population consisted of all cardiac patients referring to Imam Ali Cardiovascular Hospital in Kermanshah City, Iran, in 1977. The study was performed on 30 heart patients who were randomly divided into experiment and control groups. Initially, both groups completed McNeady’s Cognitive Emotion Regulation and quality of life questionnaires as a pretest. The experimental group was then trained in emotion regulation skills based on dialectical behavior therapy, but the control group remained on the waiting list. After treatment sessions, both groups responded to the questionnaires again. To analyze the data obtained from the research questionnaires, we calculated central tendency and dispersion indices and performed multivariate analysis of covariance.
3. Results
Table 1 presents descriptive statistics on cognitive emotion regulation strategies and quality of life in the pretest-posttest of experimental and control groups.
In the positive emotion regulation strategies, the results showed a significant difference between the total scores of the subjects in the posttest of positive emotion regulation strategies. Concerning the quality of life, in the emotional performance variable, the results of the interpersonal impact test showed a significant difference between the total scores of the subjects in the posttest.

The mean score of positive and negative strategies of emotion regulation and quality of life in the experiment group was significantly different from the mean score of the control group (P<0.01). Therefore, training of emotion regulation skills based on dialectical behavior therapy had a significant effect on positive and negative strategies of emotion regulation and quality of life of the experiment group.
4. Discussion 
The purpose of this study was to investigate the effectiveness of emotion regulation training based on dialectical behavior therapy on cognitive emotion regulation and quality of life in patients with cardiovascular diseases. The results of the present study showed that dialectical behavioral emotion regulation intervention was effective in increasing the use of positive strategies and decreasing the use of negative strategies on the quality of life of these patients.
 According to the findings, psychological factors such as biophysical ones are of particular importance and should be considered in the treatment of cardiovascular diseases. On the other hand, emotion regulation training, helps individuals manage their conflicting emotions by making them aware of feeling and how to properly use of cognitive emotion regulation strategies. It also provides the basis for how emotions can be managed appropriately to improve people’s quality of life.
The limitation of our study was its low sample size that has led to caution in generalizing its results to society. The use of self-assessment and self-report questionnaires can also be another limitation of the study. Therefore, further research with larger sample size and using other forms of data collection, such as interviewing is recommended to obtain more accurate information. It is recommended to investigate the effect of this treatment on other chronic diseases to achieve more extensive results. It is also suggested that this treatment be used as a complement to drug therapy in cardiac patients.
Ethical Considerations
Compliance with ethical guidelines
This study was approved by the Research Ethics Committee of Kermanshah University of Medical Sciences (Code: IR.KUMS.REC.1397.39).
Funding
The present paper was extracted from a PhD. thesis of the first author, Seyed Vali Kazemi Rezaei, approved by the Department of Psychology, Faculty of Literature and Humanities, Kermanshah Branch, Islamic Azad University.
Authors' contributions
All authors met the writing standards based on the recommendations of the  International Committee of Medical Journal Publishers (ICMJE).
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgements
The authors would like to thank the officials and staff of Imam Ali Cardiovascular Hospital in Kermanshah and all participants in this study for their valuable cooperation.

 

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