1. Introduction
yocardial infraction is one of the main causes of mortality around the world [1]. As a life-threatening Myocardial Infarction (AMI) can exert substantial distress on patients during and after the event [3]. The resulting psychological stress may not only impair patients’ emotional well-being, but also adversely affect their cardiovascular health and post-AMI recovery [4]. Given the increasing prevalence of AMI and the emphasis on the association of socio-psychological factors with cardiovascular diseases, it is important to identify patients' stress levels, how they use coping strategies, and appropriate psychological treatment for them.
This study aimed to determine the effectiveness of Dialectical Behavior Therapy (DBT) on perceived stress and coping skills in patients after having AMI.
2. Materials and Methods
This is a randomized clinical trial codnucted in 2018 on 30 discharged patients with a diagnosis of AMI referred to Noor Heart Clinic in Rasht, Iran. The patients were divided into intervention (5 females and 10 males) and control groups (8 females and 7 males). Prior to study, necessary information about the intervention was provided to the participants and a written informed consent was obtained from them. The appropriateness of the treatment for the participants was also ensured. In order to observe the principle of confidentiality, the information obtained from the participants were encoded.
The DBT was presented at 8 sessions of 90 minutes. The control group received common medications only. Perceived stress and coping skills of the patients were assessed before and after the end of inetrvention and during 3-month follow-up (period) by a three-part self-report questionnaire consisting of form surveying demographic and health-related characteristics (age, gender, marital status, educational level, income level, living status, duration of disease, history of hospitalization over the past 6 months), the Persian version of the Perceived Stress Scale-14 items (PSS-14) [5], and the Ways of Coping Questionnaire (WCQ) with 66 items developed by Lazarus and Folkman [6], evaluating the problem-focused and emotion-focused coping strategies in patients. Pre- and post-intervention assessments were also performed on patients in the control group and their feelings and experiences were surveyed. Data were analyzed using independent t-test, repeated measures ANOVA, and Bonferroni Post Hoc test.
3. Results
At baseline, there was no significant difference between the two study groups in terms of age, according to the results of independent t-test; no significant difference in terms of education level according to the results of chi-square test; and no significant difference in terms of the pre-test scores of PSS-14 and WCQ (P>0.05). The results of repeated measures ANOVA showed the significant effect of DBT on perceived stress (F=6.21, P<0.05), problem-focused coping strategy (F=5.00, P<0.05) and emotion-focused coping strategy (F=15.20, P<0.001) in three pre-test, post-test, and follow-up stages in the intervention group compared to the control group. The results of Bonferroni post hoc test for the intervention group showed a significant difference in perceived stress and emotion-focused strategy between the pre-test, post-test, and pre-test/follow-up stages (P<0.05), but no significant difference was observed between the pre-test and follow-up stage in the problem-focused strategy (P>0.05). Moreover, no significant difference was observed in any variables between the post-test and follow-up stages (P>0.05).
4. Conclusion
In this study, we investigate the effects of DBT on perceived stress and coping skills in patients after AMI. We tried to identify factors affecting the disease in these patients. We found that DBT can reduce perceived stress and improve coping skills in these patients. After DBT, negative self-reported emotions (such as anxiety and stress) in the patients were replaced with postive emotions.

Ethical Considerations
Compliance with ethical guidelines
The present study has been approved by the Ethics Committee of Islamic Azad University, Rasht Branch (IR.IAU.RASHT.REC.1399.006).

Funding
This article was extracted from the PhD. dissertation of first author, Department of Psychology, Rasht Branch, Islamic Azad University, Rasht. 

Authors' contributions
Conceptualization: Azam Nourisaeed; Methodology, software, validation, formal analysis, investigation, resources: Azam Nourisaeed, Shohreh Ghorban Shiroudi; Data curation, writing – original draft preparation, writing – review & editing: Azam Nourisaeed; Visualization, supervision, project administration: All authors.

Conflicts of interest
The authors declare that there is no conflict of interest.

Acknowledgements
The authors would like to thank the Staffs of Noor Heart Clinic.


References