Introduction

Myocardial infarction (MI) is a life-threatening cardiovascular condition and a major cause of sudden cardiac death (1). MI with non-obstructive coronary arteries (MINOCA) is a working diagnosis characterized by the acute presentation of MI with no significant stenosis of the coronary arteries after angiography (stenosis <50%) (2, 3). MINOCA accounts for approximately 6%−15% of all patients with acute MI (4-6).

Sleep is a complex physiological process that occupies approximately one-third of human life and plays a fundamental role in maintaining overall health. Increasing evidence suggests that both sleep duration and sleep quality are important determinants of health outcomes (7, 8). Many studies showed a relationship between sleep duration and its quality with the prevalence of cardiovascular diseases (CVDs) (9) and both are risk factors for CVDs (10, 11). Some studies suggest that poor sleep quality may be a potentially modifiable predictor of prognosis in the patients with coronary heart disease (CHD) (12, 13). In recent years, growing evidence suggests a strong association between myocardial infarction and depression, with each condition potentially influencing the onset and progression of the other (14, 15). Besides, depression has a significant negative impact on the prognosis of MI patients, whether the depression occurred before or after it (16). Anxiety is a widespread public health issue that has an impact on many patients' and their families' lives. According to some research, individuals with MINOCA may have higher levels of anxiety than those with obstructive MI (5, 6, 17). There are many theories about the correlation among anxiety, depression, and CHD, such as disturbances in the autonomic nervous system and hypothalamic-pituitary-adrenal axis that can increase sympathetic nerve activity and catecholamine secretion, causing inflammation and platelet activation (18).

Sleep disorders are highly prevalent among patients with MI and may worsen clinical prognosis. In addition, psychological symptoms such as anxiety and depression can adversely affect sleep quality. Besides, the mechanisms of the relationship between sleep components and psychological symptoms with heart diseases are not yet known. Despite increasing evidence regarding psychological symptoms after MI, comparative evidence between obstructive MI and MINOCA remains limited and inconsistent, particularly regarding the coexistence of sleep disturbances, anxiety, and depression. Moreover, little is known about these relationships in Middle Eastern populations. Therefore, this study aimed to compare sleep quality, anxiety, and depression between patients with obstructive and non-obstructive myocardial infarction.

Methods

In this cross-sectional study, 282 of 302 eligible patients admitted to Dr. Heshmat Hospital in Rasht, Iran, in 2023 agreed to participate. Participants were equally allocated into two groups, including 141 patients with obstructive myocardial infarction and 141 patients with non-obstructive myocardial infarction (Figure1). The sample size was calculated a priori using G*Power software (version 3.1). The calculation was based on the objective of detecting a significant difference in the mean anxiety scores between the two independent groups (obstructive MI vs. non-obstructive MI). The primary input parameters were derived from a previous study by Daniel et al. (2018) (19), which reported mean anxiety scores of 5.5 ± 4.3 (Mean ± SD) for patients with non-obstructive MI and 4.2 ± 3.4 for those with coronary artery disease. Using the independent t-test (two-tailed) model, with a significance level (alpha) of 0.05 and a statistical power (1 - β) of 0.80, the calculated effect size (d) was approximately 0.34. The software indicated that a minimum of 141 participants per group (total N = 282) was required to achieve the desired power. Considering potential non-participation, all eligible patients during the study period (2023-2024) were invited, and the final sample met this calculated requirement.

According to the 2018 European Society of Cardiology (ESC) criteria, MI was defined as elevated cardiac troponin levels accompanied by at least one of the following: symptoms of myocardial ischemia, new ischemic electrocardiographic changes, pathological Q waves, imaging evidence of new loss of viable myocardium or regional wall motion abnormality consistent with ischemia, or identification of a coronary thrombus by angiography or autopsy (20).  MINOCA disease according to the European Society of Cardiology included: (1) definite diagnosis of AMI, (2) coronary angiography without coronary occlusion (<50% stenosis) in any major vessel, and (3) no specific alternative diagnosis Other for acute manifestations (21). Patients <18 years, with dementia or cognitive impairment, with an incurable disease, with a life expectancy of <1 year, were excluded

Patients’ demographic data including age, sex, education level, marital status was collected. The Pittsburgh Sleep Quality Index (PSQI), patient health questionnaire-9 (PHQ-9) and generalized anxiety disorder-7 (GAD-7) were used to assess patients.

PSQI includes 9 questions in 7 dimensions: subjective sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbances, use of sleep medications, and daytime dysfunction with 4 open questions and 5 multiple-response items. The total score of the 7 dimensions of the questionnaire forms the total score of the questionnaire, which ranges from 0 to 21. In addition, each questionnaire has a score between 0 and 3. Higher score represents lower sleep quality (22).

The PSQI is well validated in both clinical and community populations, making it a reliable tool in sleep research and clinical practice for assessing sleep disturbances and overall sleep quality (23, 24).

PHQ-9 is a questionnaire that measures the presence and severity of symptoms related to depression. This instrument consists of nine questions that ask about the frequency and severity of things such as sadness, low mood, and loss of interest or pleasure in activities, feelings of worthlessness or guilt, and thoughts of self-harm. Each question is scored on a scale from 0 to 3 based on frequency and severity, with higher scores indicating more severe symptoms. A score of 5 or lower indicates mild depression, while a score of 10 or higher indicates moderate to severe depression. The Persian version of PHQ-9 has demonstrated good psychometric properties among different population (25). In this study, the Cronbach's alpha coefficient of PHQ-9 was 0.847.

GAD-7 tool has seven main questions and one additional question that measures the presence of generalized anxiety disorder and the degree of interference of the disorder in the person's functioning. Questions are graded on a Likert scale from 0 to 3. The scores obtained in each of the seven main questions are added together to obtain the total anxiety score for the scale, which ranges from 0 to 21. The Persian version of GAD-7 has demonstrated good psychometric properties (26). The GAD-7 was selected due to its brevity, ease of administration in medically ill populations, and previously established validity and reliability of the Persian version in Iranian populations. In this study, the Cronbach's alpha coefficient of GAD-7 was 0.83.

In this study, continuous variables were expressed as mean (standard deviation (SD)) and categorical variables as n (%). The relationships between PSQI, PHQ, GAD scores and the likelihood of having obstructive myocardial infarction were analyzed using logistic regression, with a series of models applied to adjust for potential confounding variables. Variables included in the multivariable logistic regression models were selected based on clinical relevance and potential associations identified in preliminary analyses. Age, sex, and residential location were included as potential confounding variables. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) were reported. Statistical analyses were performed using SPSS version 22.0 (SPSS Inc., Chicago, IL, USA). A P-value < 0.05 was considered statistically significant.

Ethical Consideration

This article is the result of a research project approved by Guilan University of Medical Sciences. To ensure the protection of participants' rights, the researcher obtained approval from the research ethics committee of Guilan University of Medical Sciences (IR.GUMS.REC.1402.204), and informed consent was obtained from each participant.

Results

The mean age of participants in the obstructive MI group was 60.46 ± 10.30 years, compared with 56.36 ± 11.07 years in the non-obstructive MI group.

As shown in Table 1, significant differences were observed between the two groups regarding sex distribution (p=0.001), Job status (p=0.018) and residential location (urban/rural) (p=0.007). The obstructive MI group included a higher proportion of male patients, whereas the non-obstructive MI group had a greater proportion of female patients. No statistically significant differences were found between the groups in marital status, comorbidities, employment status, educational level, sleep quality (PSQI), or depressive symptoms (PHQ-9). However, anxiety levels (GAD-7) differed significantly between the groups (p=0.024).

Multivariable logistic regression analyses were conducted to examine the independent association between MI type and psychological outcomes after adjustment for potential confounders (Table 2). After adjustment, no statistically significant association was observed between MI type (obstructive vs. non-obstructive) and poor sleep quality, depressive symptoms, or anxiety levels. Patients with obstructive MI had similar odds of poor sleep quality (OR = 1.19, 95% CI: 0.69–2.05; p=0.520), depression (OR = 1.36, 95% CI: 0.85–2.15; p=0.190), and anxiety (OR = 1.20, 95% CI: 0.75–1.93; p=0.432) compared with patients with non-obstructive MI.

However, sex differences were consistently observed across all adjusted models. Male patients had significantly lower odds of poor sleep quality, depressive symptoms, and anxiety than female patients. In addition, residential location showed a significant association with depressive symptoms, as urban residence was associated with lower odds of depression compared with rural residence. No significant relationship was observed between age and any of the studied psychological outcomes.

Table 1. Baseline Characteristics of the Study Population

^*Chi-square test, ^** Independent t-test. Pittsburgh Sleep Quality Index (PSQI), patient health questionnaire (PHQ) and generalized anxiety disorder (GAD)

Table 2. Multivariable logistic regression analysis of the association between type of MI and sleep and psychological outcomes (N=282)

MI (myocardial infarction) Pittsburgh Sleep Quality Index (PSQI), patient health questionnaire (PHQ) and generalized anxiety disorder (GAD)

Discussion

In this study, sleep quality, depressive symptoms, and anxiety levels were evaluated in obstructive MI versus MINOCA patients. The findings revealed that no statistically significant association between MI classification (obstructive vs. non-obstructive) and concurrent sleep quality, depression, or anxiety, following adjustment for key confounders. The comparable odds of impaired sleep and heightened psychological symptoms across both groups indicate that the specific anatomical nature of the MI might not be a critical factor in shaping these acute patient-reported outcomes. These results were contrary to previous studies (27-34). This discrepancy may be attributed to differences in study timing, cultural contexts, assessment tools, or the specific confounding variables adjusted for in the analysis. Our findings imply that during the acute post-MI period, the psychological and sleep challenges faced by patients are considerable and pervasive, regardless of the obstructive nature of their coronary arteries. This underscores the necessity of routine, universal screening for sleep disturbances, anxiety, and depression in all MI patients, not just those perceived to be at higher risk based on coronary anatomy. Another possible explanation for the lack of observed differences between groups is that the emotional impact of receiving a diagnosis of myocardial infarction may itself overshadow distinctions related to coronary obstruction status. Regardless of angiographic findings, patients with MI commonly experience fear of recurrence, uncertainty about prognosis, physical limitations, and concerns about mortality, all of which can contribute substantially to anxiety, depressive symptoms, and sleep disturbances. Therefore, it is plausible that the shared psychological consequences of MI outweigh differences attributable to obstructive versus non-obstructive pathology (28, 31, 33).

An important finding of this study was the strong and consistent association between female sex and poorer psychological and sleep outcomes. Women had significantly higher odds of depression, anxiety, and poor sleep quality compared with men across adjusted models. This finding aligns with previous evidence indicating greater psychological vulnerability among women following cardiovascular events (27, 28, 35).

Several mechanisms may explain this disparity. Biologically, hormonal fluctuations and sex-related neuroendocrine responses may influence emotional regulation and stress adaptation. Psychosocially, women often report higher caregiving burdens, lower perceived social support, and greater emotional distress after major illness. Additionally, women with cardiovascular disease may experience delays in diagnosis or under-recognition of symptoms, potentially contributing to heightened psychological burden. These findings emphasize the importance of adopting gender-sensitive approaches in post-MI care and rehabilitation programs (28, 31, 33, 36).

Interestingly, residential location emerged as another relevant factor, with urban residence associated with lower odds of depressive symptoms compared with rural living. This association may reflect differences in access to healthcare services, mental health resources, socioeconomic opportunities, transportation infrastructure, and social support systems (36, 37). Rural populations may face greater barriers to specialized cardiac follow-up and psychological care, potentially increasing emotional distress after MI. However, the absence of a similar association with anxiety or sleep quality suggests that geographical influences may affect psychological domains differently. Future studies should further investigate environmental and socioeconomic determinants of psychological recovery following myocardial infarction.

Although sleep quality, anxiety, and depression did not significantly differ according to MI subtype in the present study, these outcomes remain clinically important in patients recovering from myocardial infarction. Previous evidence suggests that sleep disturbances and psychological symptoms are highly prevalent after MI and may adversely affect recovery, quality of life, and long-term cardiovascular prognosis (12, 13, 34). Therefore, the absence of statistically significant differences between obstructive MI and MINOCA in our study should not diminish the importance of routine screening and management of these symptoms. Instead, our findings support the need for comprehensive psychosocial assessment in all MI patients, regardless of coronary obstruction status.

Several limitations should be acknowledged. First, the cross-sectional nature of this study precludes causal inference and prevents evaluation of temporal relationships between myocardial infarction type and psychological outcomes. Second, the use of self-report questionnaires introduces the possibility of recall bias and reporting bias, despite the use of validated instruments. Third, participants were recruited from a single referral center in northern Iran, which may limit external validity and generalizability to other healthcare systems or sociocultural settings. Fourth, although several demographic variables were adjusted for, residual confounding related to factors such as prior psychiatric history, medication use, severity of cardiac dysfunction, social support, and socioeconomic status could not be fully excluded. Finally, psychological symptoms may evolve over time; therefore, longitudinal studies are needed to examine trajectories of sleep quality, anxiety, and depression during different phases of MI recovery.

Implications for practice

The findings of this study support the integration of routine psychosocial assessment into post-myocardial infarction care for both obstructive MI and MINOCA patients. Since sleep disturbances, anxiety, and depressive symptoms were observed regardless of MI subtype, clinicians should avoid limiting psychological screening to patients with severe coronary obstruction. The use of brief validated tools such as the PSQI, PHQ-9, and GAD-7 during hospitalization or early outpatient follow-up may facilitate timely identification of vulnerable patients. Particular attention should be given to female patients and individuals living in rural areas, who may be at greater risk of adverse psychological outcomes. Integrating mental health support, sleep counseling, and referral pathways into cardiac rehabilitation programs may improve recovery, treatment adherence, and quality of life following myocardial infarction.

Acknowledgments

The authors would like to acknowledge the Vice-Chancellor for Research of Guilan University of Medical Sciences for financial support.

Conflicts of interest

The authors declare that they have no competing interests.

Funding

This study was funded by Guilan University of Medical Sciences.

Authors' Contributions

Arsalan Salari designed and supervised the study protocol. Bahare Gholami Chaboki, Yasaman Borghei, Zahra Ahmadnia contributed to data interpretation and statistical analysis. Bahare Gholami Chaboki, Yasaman Borghei, Zahra Ahmadnia prepared the manuscript and Fatemeh Jalali, Azam Nourisaeed, Arezoo Javadzadeh-Moghtader, Hadis Akbarinezhad collected the data. All authors have read and agreed to the published version of the manuscript.

Artificial Intelligence statement

The authors have not used any AI tools or technologies to prepare this manuscript.