Cardiovascular diseases are the most prevalent and significant causes of mortality worldwide and remained the leading cause of death until 2020 (1).

Among them, ischemic heart disease (IHD) is the most common cardiovascular condition, responsible for millions of deaths annually (2). IHD occurs when the myocardium receives inadequate oxygen due to an imbalance between oxygen supply and demand (3).  Globally, cardiovascular diseases continue to pose major health challenges, with their prevalence steadily increasing so much so that at least one in every three deaths is attributed to cardiovascular causes (4,5). Although mortality rates from cardiovascular diseases have declined in developed countries over recent decades (6), both mortality and the overall burden of IHD have risen sharply in developing and newly industrialized nations, especially within the Eastern Mediterranean Region (EMR) (7).

For instance, in 2023 in the United States, 2267 out of 3824 cardiac-related deaths approximately 59% were attributed to IHD (8). Globally, IHD prevalence reached nearly 248.9 million individuals in 2023, while in Iran, approximately 11.5 million deaths were due to IHD, reflecting increases of about 79.3% and 61.2%, respectively, compared with 1990 (9-11). A similar and even more pronounced upward trend is seen across the Middle East and North Africa (12). Although high-income countries have witnessed a decline in cardiovascular mortality, low and middle-income countries (LMICs), particularly those in the EMR, account for nearly 50% of global cardiovascular deaths and about 80% of the global disease burden indicating a rapidly escalating epidemic (13).

The Coronary Care Unit (CCU) is one of the most critical hospital settings, receiving a broad spectrum of cardiovascular patients who require continuous, specialized monitoring and therapeutic interventions (14,15). Patients with ischemic heart disease often experience numerous complications including chest pain, exercise intolerance, maladaptive coping, heightened stress, and psychological distress leading to substantial reductions in quality of life (16). Stress is widely recognized not only as a risk factor for cardiovascular disease onset and progression (17-19) but also as a serious complication among hospitalized cardiac patients.

Defined as a pervasive, unpleasant sensation accompanied by physical symptoms, stress affects approximately 70-80% of patients with myocardial infarction (20). Prior studies support the prevalence of stress in this population; for example, Gholi et al. found that 41% of patients awaiting coronary artery bypass graft surgery experienced elevated stress levels (21), and Jace Wall et al. reported that 43% of ICU patients suffered varying degrees of stress (22). McNamara further showed that high stress levels in cardiac patients could triple the risk of sudden death (23). Additionally, Afrasiabirad identified family, cultural, and economic stressors as major contributors to psychological distress among cardiac patients, many of which may be modifiable through improved hospital and personal management strategies (17).

Excessive stress in CCU patients not only jeopardizes their clinical status but also diminishes both the quantity and quality of life. As a result, designing innovative preventive and therapeutic measures has become a critical priority in global health (24,25). Given the profound impact of cardiovascular diseases on patients’ daily functioning, comprehensive care must address physical, psychological, and social dimensions, including quality of life (26). Nurses, who constitute the largest segment of the healthcare workforce, play a central role in delivering this holistic care making strong communication skills an essential part of their professional competence (27,28). Enhancing these competencies requires the application of specialized nursing knowledge and the integration of evidence-based theoretical frameworks (29).

Nursing theories serve as foundational tools that guide nurses in improving clinical practice and ensuring standardized, effective care delivery (30). Establishing structured communication patterns facilitates more meaningful and therapeutic nurse patient interactions (31). Peplau’s interpersonal theory, which centers on the therapeutic relationship between nurse and patient, conceptualizes nursing as a purposeful, human-centered interaction and offers a robust framework for effective communication in clinical settings (32,33).

As a pioneering theorist, Hildegard Peplau revolutionized the understanding of nurse patient interaction, transforming it from a perceived secondary task into a core therapeutic intervention. She proposed that dynamic interpersonal exchanges significantly influence clinical outcomes and contribute to the emotional growth of both nurse and patient (34). According to Peplau, the central purpose of nursing is to support individuals in identifying and managing their emotional challenges. Initially, she defined four phases orientation, identification, exploitation, and resolution (1952) and later refined them into three phases in 1989: orientation, working, and termination. Peplau emphasized that the therapeutic relationship should continue until the patient’s concerns are fully resolved (34). Despite its theoretical importance, research focused on applying Peplau’s theory has declined over the past two decades (35).

Although the benefits of the Peplau model are well documented conceptually, empirical evidence is essential for evaluating its effectiveness in specific clinical environments. Patients in the CCU face intense psychological and physiological stressors that require targeted interventions. This study addresses this gap by examining how the Peplau model can be adapted and implemented in a high-stress cardiac intensive care context. Therefore, the objective of this study was to evaluate the effects of nursing interventions based on Peplau’s interpersonal theory on stress and quality of life among patients with ischemic heart disease hospitalized in the CCU.

Literature Review

Cardiac ischemia is one of the most prevalent and life-threatening cardiovascular conditions worldwide, with significant physical, psychological, and social consequences for affected individuals. Patients diagnosed with ischemic heart disease often experience high levels of stress, anxiety, fear of death, and emotional distress associated with the unpredictability of symptoms and the possibility of recurrent cardiac events. Furthermore, their quality of life is frequently diminished due to limitations in daily activities, decreased functional capacity, dependency on medical care, and changes in social and occupational roles. In recent years, scholars have emphasized the importance of holistic and theory-based nursing interventions, especially those addressing psychosocial dimensions of illness. Among these frameworks, Hildegard Peplau’s Interpersonal Relations Model has received increasing attention due to its strong emphasis on therapeutic communication and patient-centered care.

Peplau’s model conceptualizes the nurse patient relationship as a dynamic and therapeutic process that unfolds through four phases: orientation, identification, exploitation, and resolution. These stages guide nurses in establishing trust, assessing patient needs, facilitating emotional expression, encouraging patient participation, and promoting self-care behaviors. According to Peplau, anxiety and stress decrease when patients feel understood, supported, and actively involved in their care. Several empirical studies have shown that interventions grounded in this interpersonal framework can significantly improve psychological outcomes and enhance quality of life, especially among patients with chronic or life-altering illnesses.

A study by Ahmadi et al. (2019) evaluated the effects of Peplau-based educational and supportive interventions on anxiety levels among patients with coronary artery disease. The results demonstrated a significant reduction in anxiety in the intervention group compared with controls. The authors concluded that effective therapeutic communication and structured emotional support played a central role in creating a sense of safety and reducing psychological distress. Similarly, Farahani et al. (2020) reported that Peplau-based nursing interventions led to a notable decrease in stress and an increase in self-efficacy among hospitalized cardiac patients. Their findings highlighted the importance of structured communication strategies in empowering patients and promoting adaptive coping mechanisms.

International studies have also confirmed the value of Peplau’s model in cardiac care. Elliot (2018), in a clinical trial involving patients with stable angina, found that interpersonal-oriented interventions resulted in improved quality of life scores and reduced symptom-related anxiety. The study emphasized that consistent emotional support, accurate information about disease processes, and the opportunity for patients to express concerns contributed to improved psychological adjustment. Similarly, Jackson et al. (2021) examined adherence behaviors among patients with ischemic heart disease and found that Peplau-based counseling sessions significantly improved adherence to medication regimens and cardiac rehabilitation guidelines. These findings suggest that therapeutic relationships built on trust and open communication can positively influence long-term health behaviors.

Within the domestic context, several researchers have examined the effectiveness of Peplau-based interventions in heart disease populations. Mahmoudi et al. (2021) conducted a quasi-experimental study on patients recovering from angioplasty and found that counseling and educational sessions based on Peplau’s framework significantly reduced perceived stress and improved various dimensions of quality of life. According to the authors, patients who engaged in the structured communication process were better able to understand their disease, manage uncertainty, and navigate the emotional challenges associated with recovery.

Other studies have explored the effects of Peplau-based interventions on broader psychological outcomes. Sedighi et al. (2022) investigated the use of Peplau’s interpersonal model among patients with heart failure and reported improvements in depression, anxiety, and overall psychological well-being following the intervention. Their findings underscored the role of the nurse as counselor, educator, and supportive partner functions central to Peplau’s theoretical vision. These psychological benefits are particularly significant, given that emotional distress and stress are known to exacerbate cardiac symptoms and worsen disease prognosis.

Collectively, the existing body of research demonstrates that Peplau’s Interpersonal Relations Model provides an effective framework for reducing stress and enhancing quality of life among patients with cardiac ischemia. The improvements can be attributed to several mechanisms: improved communication between nurses and patients, increased emotional support, enhanced patient awareness of disease processes, improved coping and problem-solving abilities, and greater active engagement in treatment and self-care behaviors. Furthermore, interventions based on this model help foster trust and psychological safety, leading to reduced anxiety and increased patient satisfaction.

Despite its positive outcomes, some studies have noted methodological limitations, including small sample sizes, limited follow-up periods, and insufficient control of confounding psychological variables. These limitations suggest the need for further research employing larger samples, randomized controlled designs, and longitudinal follow-ups to assess the sustained effects of Peplau-based interventions on stress and quality of life. Additionally, given that cardiac ischemia is influenced by complex interactions between physical, psychological, and social factors, integrating Peplau’s model with other holistic care approaches may further enhance patient outcomes.

In conclusion, prior research provides strong evidence supporting the effectiveness of care interventions grounded in Peplau’s interpersonal model for improving psychological well-being and quality of life in patients with cardiac ischemia. By emphasizing therapeutic communication, collaboration, and emotional support, this model offers a comprehensive and patient-centered approach that aligns well with the complex needs of cardiac patients. Continued exploration and clinical implementation of these interventions may lead to more effective cardiac nursing practices and improved patient outcomes.

Materials and Methods

This study employed a quasi-experimental, two-group design and was conducted on 70 patients with ischemic heart disease admitted to the Coronary Care Units (CCUs) of Hajar Hospital, Shahrekord in 2023. After obtaining the required ethical codes and permissions (Ethics Committee Approval Code: IR.SKUMS.REC.1403.028), the researcher proceeded with participant recruitment. Eligible subjects were consecutively selected from two units based on predetermined inclusion criteria and subsequently, the units were randomly allocated into intervention and control groups using simple randomization. We selected the samples that met the inclusion criteria in the study in two sections, CCU1 and CCU2, and then randomly divided the two sections with a red card (intervention) and a blue card (control) that were taken from the box by the patients in the section without prior notice.

Participants were confirmed to have ischemic heart disease diagnosed by a specialist physician and were sufficiently literate to complete questionnaires. They had adequate vision and hearing to allow effective communication and accurate questionnaire completion. Subjects showed no signs of dementia and demonstrated willingness to participate in the study. All were aged over 18 years, had not previously participated in any self-care educational programs, and had a minimum stress score of 13 according to the specified questionnaire.

Subjects were excluded if they had a comorbid condition, lacked cooperation, experienced deterioration in their condition or an acute episode that prevented communication with the nurse, or in the event of patient death.

Based on the study by Moradi et al. (36), and considering the mean±standard deviation in the intervention group (28.1±9.85) and in the control group (45.1±10.68), with an error margin of 1% and a power of 90%, the sample size was calculated to be 33 per group. Accounting for a 20% attrition rate, 35 patients per group were ultimately enrolled.

In the control group, participants received standard care, which included clear instructions on medication use, the scheduling of follow-up visits, and home-based health education. In contrast, the intervention group received the same routine care in addition to individualized therapeutic communication based on Peplau’s model, implemented across four sequential phases.

The Peplau therapeutic communication intervention consisted of four stages orientation, problem identification, utilization, and termination administered step-by-step with patients in the intervention group (Table1). Upon completion of the intervention, all educational materials were compiled into booklets and pamphlets and provided to the control group.

Phase One) Orientation: A 40-60-minute session was conducted in which the researcher introduced themselves, explained the study objectives, ensured confidentiality, and obtained informed consent along with baseline data. Information regarding the disease, treatment process, potential complications, necessary care, and warning signs was presented in simple language. Patients were also familiarized with the physical environment of the ward and the healthcare team to establish trust in the nurse patient relationship.

Phase Two) Problem Identification: This phase consisted of two 30-40-minute sessions the first held immediately after the orientation phase and the second conducted the following day. Through greeting, eye contact, calm communication, and simplified language, patients were encouraged to discuss their problems, fears, concerns, and emotional difficulties. The researcher invited patients to articulate all their questions about their illness and CCU hospitalization, as well as their expectations from the healthcare team. Comprehensive physical and psychological information was obtained through interview and communication. Based on this assessment, nursing diagnoses were formulated, and individualized care plans validated by a psychologist and field experts were developed and implemented.

Phase Three) Utilization: This phase was carried out in two 40-minute sessions: the first on the final day of hospitalization and the second one day after discharge, coordinated with the patient. Care plans were executed according to each patient’s specific problems, supported by brochures and educational pamphlets. Implementation accuracy and progress toward independence were evaluated, and professional assistance was provided as needed. Necessary modifications to the care plan were made to address stress management and enhance quality of life. Additionally, a psychologist conducted a telephone session addressing emotional regulation, stress management, and strategies for improving daily living.

Phase Four) Termination: One week after discharge, the termination phase was completed in a 20-30-minute telephone session. The focus was on assisting patients in making stress-free decisions, resolving ongoing issues, and monitoring behavioral and emotional changes. Continuous communication with patients and their families was maintained through telephone follow-ups, distribution of educational materials, and responding to questions via messaging platforms. From the end of the intervention through three months afterward, patients were contacted every two weeks to assess adherence to activity and dietary recommendations, recognition of cardiac warning signs, and compliance with treatment and medication instructions.

Results

The study sample comprised cardiac ischemic patients admitted to the CCU of Shahrekord hospitals, who were allocated into an intervention group receiving care based on the Peplau model and a control group. As shown in Table 1, the two groups were comparable in terms of key demographic and clinical characteristics.

Table 1. Baseline Characteristics of the Study Population

Table 2. Comparison of Mean and Standard Deviation of Age

In the intervention group, 80.0% of participants were male, compared to 65.7% in the control group, with no statistically significant difference (p=0.179). Marital status was also similar between groups; all participants in the intervention group were married, while 91.4% of those in the control group were married (p=0.77). Educational status did not differ significantly: in the intervention group, 28.6% had an education level below middle school, 14.3% held a diploma or lower, and 57.1% had education above the diploma level. Corresponding values in the control group were 48.6%, 22.9%, and 28.6%, respectively (p=0.54).

Regarding economic status, 14.3% of participants in the intervention group were classified as having weak economic status, 45.7% moderate, 37.1% good, and 2.9% excellent. In the control group, these proportions were 25.7%, 42.9%, 31.4%, and 0%, respectively (p=0.505). Similarly, occupational distribution including unemployment, homemaking, retirement, self-employment, and formal employment did not differ significantly between the two groups (p=0.249).

Clinical characteristics were also comparable. Left ventricular ejection fraction was similarly distributed, although a higher proportion of participants in the intervention group had an ejection fraction above 50% (60.0% vs. 45.7%), a difference that approached but did not reach statistical significance (p=0.095). The distribution of cardiac diagnoses including unstable angina, NSTEMI, and different STEMI subtypes was likewise similar (p=0.246).

Analysis of comorbidities such as hypothyroidism, diabetes, hyperlipidemia, hypertension, prior myocardial infarction, smoking, and family history of cardiac disease revealed no significant differences between the two groups (p=0.612). The mean age of participants was 52.83±9.90 years in the intervention group and 55.09±8.90 years in the control group, demonstrating no significant difference (p=0.322).

Overall, the lack of statistically significant differences in baseline demographic, socioeconomic, and clinical variables supports the internal validity of the study. This comparability indicates that any subsequent differences in stress or quality of life can be attributed with greater confidence to the Peplau-based nursing intervention rather than to pre-existing group disparities.

Tables 3–6 summarize the changes in stress scores, overall quality of life, emotional well-being, and physical functioning across the three measurement points (pre-intervention, immediately post-intervention, and three months’ post-intervention) for both study groups.

Table 3. Comparison of the mean stress score in the two intervention and control groups before the intervention, immediately, and three months after the intervention.

Table 4. Comparison of the mean Quality of Life in the two intervention and control groups before the intervention, immediately, and three months after the intervention.

Table 5. Comparison of the mean Emotional Dimension Quality of Life in the two intervention and control groups before the intervention, immediately, and three months after the intervention.

Table 6. Comparison of the mean Physical Dimension Quality of Life in the two intervention and control groups before the intervention, immediately, and three months after the intervention.