Iran J Psychiatry Behav Sci. 2017 September; 11(3):e8567. Published online 2017 May 21. doi: 10.5812/ijpbs.8567. Original Article Quality of Life in Coronary Heart Disease Patients: The Role of Defense Mechanisms and Alexithymia with Mediation of Psychological Distress Isaac Rahimian Boogar, 1,* Alimohammad Rezaei, 2 and Samaneh Mohamadpoor 3 1 Department of Psychology and Educational Sciences, Semnan University, Semnan, IR Iran 2 Department of Educational Psychology, Faculty of Psychology and Education Sciences, Semnan University, Semnan, IR Iran 3 Department of Clinical Psychology, Faculty of Psychology and Education Sciences, Semnan University, Semnan, IR Iran * Corresponding author: Isaac Rahimian Boogar, Ph.D. in Health Psychology, Associate professor of Clinical Psychology, Department of Psychology and Educational Sciences, Semnan University, Semnan, IR Iran. Tel: +98-2333623300, Fax: +98-2333625554, E-mail: i_rahimian@semnan.ac.ir Received 2016 August 29; Revised 2017 January 01; Accepted 2017 March 29. Abstract Background: Coronary heart disease leads to negative consequences, diminished health-related quality of life, and increased mor- tality. Objectives: This study aimed at predicting the quality of life of patients with coronary heart disease based on defense mechanisms and alexithymia with the mediating role of psychological distress. Methods: In a cross-sectional descriptive study, 300 patients with coronary heart disease, who had referred to the specialized heart center of Ayatollah Madani governmental hospital in Khorramabad city of Lorestan were selected by the convenience sampling method from February to July 2015. Depression, anxiety, and stress scales, the mac-new health-related quality of life questionnaire for patients with heart disease, the Toronto alexithymia scale, the defensive styles scale and a demographical checklist were used for data collection. Descriptive indices were analyzed by SPSS-19 and structural equation model with AMOS was used for analysis of the inferential statistics. Results: According to the structural equation model, the path coefficient related to the effect of defense mechanisms on alexithymia (β = 0.65), alexithymia on the quality of life (β = -0.26), alexithymia on psychological distress (β = 0.51), and psychological distress on the quality of life (β = -0.58) were statistically significant (P < 0.001). However, the path of the defense mechanisms to psychological distress and the path of defense mechanisms to quality of life were not significant (P > 0.05). Conclusions: Defense mechanisms and alexithymia had a significant role in predicting the quality of life of patients with coronary heart disease. It is recommended that clinical specialists should design appropriate clinical trials or modify the current and future interventions on the basis of the results of such studies. Keywords: Affective Symptoms, Coronary Disease, Defense Mechanisms, Quality of Life 1. Background The incidence of heart diseases is rising in many soci- eties (1, 2). Among these diseases, coronary heart disease (CHD) has caused the death of 7.3 million patients around the world and led to mortality more than any other disease (1). Quality of life (QOL) includes psychological, social, and physical well-being in people with medical diseases and disabilities (3, 4). Moreover, health-related quality of life is a reflection of the effects of the disease and their treat- ments with regards to the patient’s views and experiences (5). Coronary Heart Disease has many adverse effects on health-related QOL (4, 6). In order to promote the quality of life of patients with CHD, it is necessary to examine factors affecting this dis- ease (2). In the recent years, strong and cohesive studies have provided data on the high importance of psycholog- ical factors in the etiology and exacerbation of cardiovas- cular diseases (7). Psychological distress, including depres- sion, anxiety, and stress, are of the most important factors in morbidity and mortality among patients with CHD (7, 8). Depression as the most common psychological state has a strong effect on increased incidence, inappropriate prognosis, and increased mortality in patients with CHD (9, 10). Similarly, higher levels of anxiety and stress in pa- tients with CHD decrease the QOL and increase mortality (11, 12). Patients with heart disease are at greater risk of anxiety and psychological stress due to a lack of adaptive defense mechanisms and maladaptive coping with stress (13). Defense mechanisms and alexithymia are important personality traits related to QOL and psychological distress in the patients (14, 15). Defense mechanisms are uncon- scious psychological processes that protect the patients against anxiety and internal or external threats by reduc- Copyright © 2017, Iranian Journal of Psychiatry and Behavioral Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/) which permits copy and redistribute the material just in noncommercial usages, provided the original work is properly cited.