Introduction

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 month1. People with ASD usually exhibit behaviors such as crying and apathy towards life2. 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 life3.

ASD was found to be prevalent in 18% of patients with acute coronary syndromes (ACS), such as AMI4. ASD is associated with impaired quality of life and adverse cardiovascular consequences after ACS5,6. 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 elderly7. 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 community8. 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 events9,10. 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 distress11. 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 behavior12. 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 symptoms13. The study flow chart is illustrated in Fig. 1.

Figure 1
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Patient flow chart.

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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 questionnaires 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.

‘In-hospital complications’ include in-hospital hemorrhagic stroke, ischemic stroke, cardiopulmonary resuscitation, heart failure, hypotension requiring vasopressors and arrhythmia.

‘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’ ASD14. 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 attachment-related 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 1 Score of acute stress disorder in young and middle-aged patients with acute myocardial infarction (n = 190).
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Table 2 Differences in the participants’ ASD based on demographic characteristics [n = 190, M(P25, P75)].
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Relationships between ASD, social support and adult attachment

The score of social support for this study was 36.01 (± 9.72) points: 8.83 (± 2.76) points for objective support, 20.23 (± 5.89) for perceived support and 6.94 (± 2.77) for support utilization. The score of attachment-related anxiety was 48.06 (± 14.83) points and that of attachment-related avoidance was 63.44 (± 13.57). The correlations between ASD, social support and adult attachment are shown in 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).

Table 3 Correlations between ASD, social support and adult attachment (n = 190, ρ).
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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, αinclusion = 0.05, αexclusion = 0.10). The results revealed a significant regression model (F[9,180] = 11.404, p < 0.001), with an adjusted coefficient of determination (adjusted R2) 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).

Table 4 Evaluation of independent variables.
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Table 5 Multivariate stepwise regression results of ASD (n = 190).
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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. Attachment-related 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.

Table 6 Hierarchical regression analysis for ASD.
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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 (χ2/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).

Figure 2
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Path model explaining the effects of determinants.

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Table 7 Decomposition of standardized effects from the path model.
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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 reported4. Roland found that AMI patients with ASD or PTSD were younger than those without, although their coronary heart disease severity was relatively mild18. 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 severity20. Anxiety or PTSD is more frequently observed in people with higher disease severity21,22. 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 decreases23. Similar to previous studies, we found that social support helps deter negative emotions24. According to Norris et al.’s social support deterioration deterrence model, social support, as an external protective factor, plays an essential role in buffering the adverse effects of stress response10. 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 levels25. 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 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 stress26. 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 pressure12.

On the physiological level, patients with greater attachment-related anxiety secrete more cortisol when faced with stressful events27. Previous studies have shown that excess cortisol may induce major depression disorder in individuals28. 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 with others and may even avoid seeking help29. Girme et al. suggested that receiving low-to-moderate practical support from one’s partner increased distress risk in avoidant participants30. 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 effectively31.

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.

Limitations

This study has several limitations. Firstly, participants in this study were recruited using the convenient sampling method, so they may not be representative of all young and middle-aged AMI patients in China. Secondly, according to DSM-5, female patients are more prone to develop acute stress disorder. Previous research showed that women are more likely to develop ASD after traumatic experiences32. However, our study did not support any association between sex and ASD, although the total SASRQ score for female patients was slightly higher than that of male patients. This is consistent with Marie-Anne Roberge’s research results33 and suggests that it is necessary to collect more samples from different regions to explore ASD symptoms further and their relationship with sex in AMI patients. Thirdly, cross-sectional data analysis cannot be used to explain causality directly. Future longitudinal studies may be needed to confirm our findings.

Conclusions

Despite the above-mentioned limitations, our study still demonstrates acute psychological reactions related to AMI and related factors that can reduce ASD symptoms (such as adult attachment and social support). Identifying the risk and protective factors in early AMI treatment is essential to prevent future ASD. Existing research reports also can provide reference significance. Since the AMI severity is related to ASD, the medical personnel can reduce negative emotions by continuously improving AMI’s first aid process and minimizing related in-hospital complications. In addition, medical staff should evaluate adult attachment and social support as soon as possible, adjust the nursing plan appropriately and encourage family members’ engagement in the treatment process to prevent ASD occurrence.