The prevalence of acute stress disorder after acute myocardial infarction and its psychosocial risk factors among young and middle-aged patients

Young and middle-aged people are vulnerable to developing acute stress disorder (ASD) following acute myocardial infarction (AMI). This study aims to explore the factors that contribute to ASD in young and middle-aged AMI patients. 190 AMI patients aged 18 to 60 years were enrolled in this study. We assessed the association between ASD and demographic data, adult attachment, and social support. This study examined a total of 190 young and middle-aged people. Among them, 65 participants were diagnosed with ASD, representing a 34.21% positive rate. Multivariate stepwise regression showed that adult attachment, infarct-related artery, social support, in-hospital complications are the main factors affecting ASD. Path analysis showed that social support had mediated the relationship between adult attachment and ASD. The incidence of ASD in young and middle-aged patients with AMI is high. Social support plays an important role in adult attachment and ASD relationships. Adult attachment and social support should be incorporated into post-traumatic cardiac rehabilitation to help patients cope with traumatic occurrences.

Acute myocardial infarction (AMI) is a severe type of coronary heart disease. As a traumatic event, AMI condition can cause acute stress disorders (ASD) like anxiety, depression, numbness, and stress response, leading to increased sympathetic excitability. High sympathetic excitability leads to associated pathophysiological changes, gradually promoting or aggravating myocardial infarction and heart failure. Most people's ASD symptoms may improve after a few weeks or months. However, some people cannot recover and repeatedly suffer from numbness, avoidance, intrusion, and other symptoms, eventually developing posttraumatic stress disorder (PTSD).
PTSD is a severe mental health problem that has received considerable attention, while ASD in the early stage of trauma is often overlooked. ASD is defined as the emotional, physical, and dissociative reaction during a traumatic event and lasts for less than one month 1 . People with ASD usually exhibit behaviors such as crying and apathy towards life 2 . In addition to affecting people's psychological state, ASD can also cause physiological changes such as pain and decreased immune resistance, impairing one's quality of life 3 .
ASD was found to be prevalent in 18% of patients with acute coronary syndromes (ACS), such as AMI 4 . ASD is associated with impaired quality of life and adverse cardiovascular consequences after ACS 5,6 . Age is a predictor of ASD, and Ghada et al. found that the risk of ASD in young persons following stressful events is greater than in the elderly 7 . Being the center of the social labor force, the young and middle-aged people are at a point in their life where professional development is critical. The disease's impact on their lives and the economy is thus significantly greater than that of other age groups. However, the symptoms of ASD following AMI and the factors influencing individual susceptibility in young and middle-aged people remain unclear. Therefore, additional research on the psychological stress response of young and middle-aged AMI patients is necessary.
Additionally, it was found that an individual's social support environment has a significant impact on their psychological distress. Social support refers to social connections with other individuals, groups, and the larger community 8 . According to Norris's social support deterioration deterrence model, social support acts as a protective "cushion" in stress response. Individuals who receive social support are less likely to be impacted by stressful www.nature.com/scientificreports/ events 9,10 . Therefore, AMI may aggravate the severity of ASD symptoms by jeopardizing young and middle-aged people's social support systems. Adult attachment patterns are the basis of human relationships, influencing the association between social support and psychological distress 11 . As a traumatic event, AMI can trigger the patient's attachment system. Attachment is defined as an intimate and lasting emotional connection between individuals and others. It plays an essential role in cognition, emotion, and social behavior 12 . The effect of attachment on ASD in young and middle-aged AMI patients has not been explained in current related studies. As such, this study intends to explore the current situation of ASD in young and middle-aged AMI patients. This study aims to establish the severity of ASD and predictors of psychological distress among AMI patients more precisely.

Methods
Participants and procedure. The subjects were recruited between January 2019 and December 2020 at The Affiliated Hospital of Hangzhou Normal University. Patients meeting the following criteria were eligible for the study. Inclusion criteria: (1) diagnosed with AMI; (2) aged between 18 and 60 years old. Exclusion criteria: (1) combined with previous complications; (2) diagnosed with dementia or other psychiatric diseases; (3) having hearing or communication impairment; (4) experienced traumatic events within half a year. The subjects were assessed for the presence of ASD through a structured interview based on the DSM-5 (the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders) criteria. The diagnostic criteria for ASD according to DSM-5 mainly include: (1) witnessed, learned, or underwent an event(s) involving death, actual or threatened serious injury, actual or threatened physical or sexual violation; (2) exhibited an array of clinically significant posttraumatic re-experience, dissociative, avoidance and/ or arousal symptoms 13 . The study flow chart is illustrated in Fig. 1.
A power analysis was conducted using the G*Power 3.1 software to calculate the minimum sample size required to achieve sufficient power for the statistical analyses involved. A sample size of 152 was estimated to be required, with a power level of 0.95 and an alpha of 0.05. A total of 203 questionnaires were issued in this study, with 190 completed questionnaires returned, resulting in an effective rate of 93.6%. The subjects' mean age was 49.99 (± 8.07) years -ranging from 23 to 60 years. Most of the subjects were male (92.11%), and their mean age was 49.69 (± 8.09) years, while female subjects accounted for 7.89%, with their mean age being 51.93 (± 7.89) years.

Research ethics. This study was approved by the Ethics Committee of The Affiliated Hospital of Hangzhou
Normal University (IRB's registration number: 2019 Ethics 02-HS-46). This study complies with the international declaration of Helsinki, the ethical examination and approval measures for biomedical research involving human subjects, and applicable laws and regulations. Each participant was given an information sheet (mainly about demographic characteristics and questionnaires used in this study) and a consent form prior to their participation in the study. Informed consent from each participant was obtained before the study. Printed question- www.nature.com/scientificreports/ naires were distributed to those who agreed and consented to participate. All participants were assured that their refusal or withdrawal from the study would not affect their treatment course.

Measures.
Demographics. Demographic characteristics include sex, marital status, education, occupation, payment, number of stent implantation, in-hospital complications, cardiac function (Killip class at admission), infarct-related artery, AMI-related knowledge, smoking, alcohol consumption, substance abuse. 'Payment' was classified into three categories: "rural medical insurance" where the patient is required to pay 50% of their medical expenses; "urban medical insurance" where the patient is required to pay 30% of their medical expenses and "self-paying" where patients need to pay all their medical expenses by themselves.
' AMI-related knowledge' was identified by evaluating the patients' knowledge on the infarct-related artery, laboratory examination results, treatment measures, and possible complications of AMI (4 items). Their knowledge was classified into three levels: "completely unaware" where the patient was unaware of all 4 items; "partly aware" where the patient knows at least one item and "fully aware" where the patient fully understands all 4 items.
Stanford Acute Stress Reaction Questionnaire (SASRQ). The 30-item Stanford Acute Stress Reaction Questionnaire (SASRQ) measured participants' ASD 14 . The questionnaire assesses dissociation (10 items mainly evaluating patients' cognitive changes such as memory loss, their decline in environmental clarity and emotional changes such as numbness and lack of emotional response); re-experience of trauma (6 items primarily evaluating patients' physiological reactions like physical symptoms caused by traumatic events and behavioral changes such as constantly having unnecessary forced thoughts of past traumatic events.); avoidance (6 items mainly assessing behavioral changes in patients such as being away from others and avoiding things associated to their traumatic experiences); anxiety and hyperarousal (6 items mainly assessing patients' behavioral changes such as sleep changes and panic attacks, cognitive changes like decreased attention and emotional changes such as tension, anxiety, and irritability); and functional impairment (2 items mainly evaluating patients' physiological reactions such as impairment of physical function). SASRQ is scored on a 5-point Likert scale ranging from 0 (not experienced) to 5 (very often experienced). The score range is 0-150 points. A total score of SASRQ ≥ 40 is positive for acute stress disorder. The higher the score, the more severe the patient's acute stress disorder. The Cronbach's α coefficient of the scale was 0.87-0.95.

Experiences in Close Relationships Inventory (ECR).
The adult attachment was assessed using the Experiences in Close Relationships Inventory (ECR) 15 . ECR produces two scores: attachment-related avoidance and attachment-related anxiety. The scale contains 36 questions adopting the 7-level scoring method: strongly disagree, disagree, somewhat disagree, not sure, somewhat agree, agree and strongly agree, which are recorded as 1-7 points, respectively. Questions 3,15,19,22,25,27,29,31,33, and 35 are scored reversedly. The sum score of odd number questions equals the score for attachment-related avoidance, while the total score of even number questions refers to the attachment-related anxiety score. The higher the score, the higher the degree of attachmentrelated anxiety or avoidance. The Cronbach's α coefficient of the scale was 0.79-0.82.

Social Support Rating Scale (SSRS).
Patients' social support was measured using Xiao's Social Support Rating Scale (SSRS) 16 . The scale has ten items, including objective support (3 items), perceived support (4 items), and support utilization (3 items). The score range is 12-66 points. A score below 35 points indicates a low level of social support, 35-45 points indicates a moderate level of social support, and a score greater than 45 indicates a high level of social support. The scale demonstrated impressive validity and reliability for the Chinese population (Cronbach's α = 0.949) 17 .
Statistical analysis. Demographic characteristics, ASD, social support and adult attachment, are all described using observed values, percentages, quartile, means, and standard deviations. The differences in the participants' ASD based on demographic characteristics were analyzed using the nonparametric rank-sum test. The relationship between social support, adult attachment, and ASD was assessed using Spearman's correlation coefficients. Additionally, multiple linear regression was used to determine the factors that influence individuals' ASD. The dependent variable was set as ASD, and the independent variables were set as perceived support, in-hospital complications, attachment-related avoidance, and attachment-related anxiety. Path analysis was performed to evaluate the mediating effect of social support on the relationship between adult attachment and ASD. The fit indices used included the root mean square error of approximation (RMSEA), comparative fit index (CFI), and normed fit index (NFI). SPSS20.0 and AMOS17.0 were used for all analyses, and the statistical significance was set at P < 0.05 (2-tailed).

Results
Preliminary analysis. A total of 190 young and middle-aged people were investigated in this study. Among them, 65 were diagnosed with ASD, with a positive rate of 34.21%. Since the total score and each dimension of ASD do not conform to the normal distribution, it was described by median (M) and interquartile spacing (P25, P75) (see Table 1). The results showed that the main symptoms of ASD were hyperarousal, reexperience and dissociation. Table 2 shows the differences in the participants' ASD based on their demographic characteristics. The results showed that ASD was significantly correlated with in-hospital complications (Z = − 2.639, p = 0.008), infarct-related artery (H = 25.840, p < 0.001), and AMI-related knowledge (H = 7.949, p = 0.019).  Table 3. ASD revealed a significant negative correlation with social support (ρ = − 0.334, p < 0.01), objective support (ρ = − 0.291, p < 0.01), perceived support (ρ = − 0.313, p < 0.01), and support utilization (ρ = − 0.251, p < 0.01). Additionally, ASD demonstrated a significant positive correlation with attachment-related avoidance (ρ = 0.374, p < 0.05) and attachment-related anxiety (ρ = 0.402, p < 0.05).

Factors influencing ASD.
Multivariate regression was used to find the components that were independently associated with ASD. The multiple linear regression analysis was conducted using the ASD total score as the dependent variable and the factors of statistical significance in nonparametric rank-sum test and correlation analyses as the independent variables. The dummy variables were set for categorical variables (the values of the independent variables are shown in Table 4, α inclusion = 0.05, α exclusion = 0.10). The results revealed a significant regression model (F[9,180] = 11.404, p < 0.001), with an adjusted coefficient of determination (adjusted R 2 ) of 0.331 for the power interpretation of the model. The contribution of independent variables to patients' ASD was sequenced as follows: attachment-related anxiety > infarct-related artery > perceived support > in-hospital complications > attachment-related avoidance based on the comparison of absolute values among variables' standardized regression coefficients (see Table 5).
The mediating effect of social support on the relationship between adult attachment and ASD. Hierarchical multiple regression analyses were conducted with perceived support and ASD as the dependent variables. Demographic characteristics were treated as the control variable, and adult attachment was entered as the independent variable. Table 6 presents the results of regression analyses. Attachmentrelated avoidance (β = 0.185, p < 0.01), attachment-related anxiety (β = 0.232, p < 0.01), and perceived support (β = − 0.193, p < 0.05) had significant effects on ASD. Path analysis was used to construct an ASD prediction model based on perceived support and adult attachment. The fit indices indicated that the path model had a good fit to the data (χ 2 /df = 1.046, GFI = 0.997, CFI = 1, NFI = 0.991, TLI = 0.997, IFI = 1, RMSEA = 0.016). The results are shown in Fig. 2 and Table 7, and they revealed that perceived support had significant direct effects on ASD (β = − 0.22, p < 0.05). The direct pathways from attachment-related avoidance to perceived support (β = − 0.35, p < 0.05) and ASD (β = 0.24, p < 0.05) were statistically significant. The bootstrapping results indicated that the indirect pathways between attachment-related avoidance and ASD through perceived support were significant (p < 0.05).

Discussion
This study examined the relationship between ASD and adult attachment and social support in young and middle-aged AMI patients, all while considering the potential impact of demographics. 34.21% of the participants developed ASD after percutaneous coronary intervention (PCI), which is higher than previously reported 4 . Roland found that AMI patients with ASD or PTSD were younger than those without, although their coronary heart disease severity was relatively mild 18 . This report confirmed that young and middle-aged people are more likely to develop ASD after experiencing cardiovascular events.
Our study showed that right coronary artery occlusion was associated with ASD. At present, there is no research report on the effect and mechanism of right coronary artery occlusion on ASD. We hypothesized that this could be due to different creatine kinase culmination. Sochman et al. reported that creatine kinase culmination (t-peak) is influenced by the necrosis site; for patients with infarction in the right coronary artery area, t-peak was 17.7 ± 4.7 h, while t-peak was 13.2 ± 4.6 h (p < 0.001) 19 for those with infarction in the left ventricle. Creatine kinase culmination reveals a significant positive correlation with infarct severity 20 . Anxiety or PTSD is more frequently observed in people with higher disease severity 21,22 . Considering ASD is a subjective psychological measure index, future studies could explore the relationship between the infarct-related artery and objective psychological measure indexes such as epinephrine and dopamine.
Additionally, increased disease severity results in increased medical expenses and recovery time for patients. When the economy affects regular treatment and life, patients' perceived social support decreases 23 . Similar to previous studies, we found that social support helps deter negative emotions 24  www.nature.com/scientificreports/ support deterioration deterrence model, social support, as an external protective factor, plays an essential role in buffering the adverse effects of stress response 10 . Social support includes the visible and objective material or emotional support that individuals obtain from their social network relationships and the emotional experience of feeling respected, supported, and understood in society. Many studies have shown that perceived social support is more natural and effective for individuals and can better predict their mental health levels 25 . As a supportive resource, perceived social support can promote communication between participants and their families, alleviating their fear caused by AMI. Notably, this study showed a positive correlation between attachment-related anxiety, attachment-related avoidance and ASD in AMI patients. Previous research showed that insecure attachment style (greater www.nature.com/scientificreports/ attachment-related avoidance or anxiety) predicted greater anxiety, depression, fasting blood glucose and glycosylated hemoglobin. Insecure attachment style is associated with poorer health outcomes in coronary heart disease patients experiencing traumatic stress 26 . As a traumatic stress, AMI can trigger the attachment system in patients; those with greater attachment-related anxiety are eager to get help from others but generally lack self-confidence and have abandonment issues. Therefore, they often exaggerate the stress events they encounter to attract attention from others, increasing their psychological pressure 12 . On the physiological level, patients with greater attachment-related anxiety secrete more cortisol when faced with stressful events 27 . Previous studies have shown that excess cortisol may induce major depression disorder in individuals 28 . In addition, patients with greater attachment-related avoidance usually treat others with a negative attitude and believe that their interpersonal relationship is unreliable-they are unable to initiate engagement Table 3. Correlations between ASD, social support and adult attachment (n = 190, ρ). **p < 0.01; *p < 0.05.  Table 4. Evaluation of independent variables.

AMI-related knowledge
The dummy variables were set with the baseline of "completely unaware" Dummy variable X 4 (completely unaware = 0, partly aware = 1, fully aware = 0) Dummy variable X 5 (completely unaware = 0, partly aware = 0, fully aware = 1)  www.nature.com/scientificreports/ with others and may even avoid seeking help 29 . Girme et al. suggested that receiving low-to-moderate practical support from one's partner increased distress risk in avoidant participants 30 . Therefore, young and middle-aged AMI patients with greater attachment-related avoidance will not actively seek help from medical staff and their families and avoid communication with others. This might strain their relationships and add additional barriers in processing their trauma effectively 31 .
Relevance to clinical practice. In our study, social support was found to be related to young and middle-aged AMI patients' psychological health. Healthcare institutions should offer psychological counseling to patients to relieve their stress. Medical staff should pay attention to their patients' psychological conditions and not simply focus on physical problems. For example, each ward can be equipped with a psychologist to provide counseling to needy patients, which might help young and middle-aged AMI patients get some psychological relief. The medical staff could motivate and improve patients' social support by using brochures or videos to encourage family members' involvement in the treatment process. Additionally, the present study suggests that adult attachment may assist in identifying those at risk of developing psychological problems. Adult attachment can be assessed routinely to help predict psychological problems in patients. Given that ASD patients are predisposed to developing PTSD, follow-up sessions with young and middle-aged AMI patients are crucial. Table 6. Hierarchical regression analysis for ASD. **p < 0.01; *p < 0.05.