All experimental procedures were approved by the Medical Ethics Committee of West China Hospital/West China School of Nursing, Sichuan University. The patient has been notified about the information contained in the consent form.

This study was conducted as a prospective, randomized, controlled, and assessor-blind trial. It aimed to explore the application of EBN intervention in reperfusion injury after PCI in patients with MI, as well as its impact on psychological state and myocardial injury. The experimental design comprised two groups, where each participant was randomly assigned to receive either conventional care (control group) or EBN intervention (intervention group) in a parallel-arm design.

The patients who underwent PCI for MI were diagnosed with postoperative reperfusion injury at West China Hospital/West China School of Nursing, Sichuan University between August 2020 and August 2022.

Inclusion criteria: Patients whose MI diagnosis conformed to the relevant criteria in the “Integrated Traditional Chinese and Western Medicine Diagnosis and Treatment Guidelines for Acute Myocardial Infarction,” and who experienced persistent pain in the anterior chest or behind the sternum for at least 30 min; patients with elevated cardiac biomarkers; patients showing peaked T waves and upwardly convex ST segments on their electrocardiograms; patients with vascular stenosis of 70% or greater; patients who voluntarily enrolled in the study and signed informed consent forms.

Exclusion criteria: Patients with serious underlying conditions; patients with malignant tumors, mental illnesses, or poor cooperation in the study; patients with incomplete data.

Participants were allocated to either the intervention or control group in a 1:1 ratio through a computer-generated random number sequence. A randomizer tool was employed to produce a unique random allocation number for each participant. These generated random numbers were securely concealed or safeguarded. The sequence of random allocations remained undisclosed to both the participants and the research team until the group assignments were finalized. An independent researcher was responsible for carrying out the group assignments by cross-verifying the random allocation numbers and allocating participants to their corresponding groups. The individuals responsible for outcome assessment and statistical analysis of the data were kept unaware of the group allocations.

During their hospital stay, the control group received conventional care, which encompassed the following: Vital signs, such as blood pressure, heart rate, and respiratory rate, were continuously monitored to ensure stability. Electrocardiogram readings were closely observed to detect any changes in cardiac activity and promptly report abnormalities. For patients requiring postoperative anticoagulant therapy, nurses were trained to understand the proper use and precautions of each medication, and this information was effectively communicated to patients. For those on other medications (e.g., beta-blockers, angiotensin receptor blockers), nurses closely monitored treatment efficacy and potential side effects. In addition, vascular access was maintained to ensure patency and prevent infections or damage to the surgical site. The surgical site was regularly checked for signs of bruising, hematoma, or bleeding, and any issues were addressed immediately. Meanwhile, individualized rehabilitation plans were created, including gradual increases in physical activity and cardiac rehabilitation, while ensuring patients did not overexert themselves. Patients were also guided through rehabilitation exercises to improve cardiopulmonary function. Psychological concerns were addressed by offering timely counseling to boost patients’ confidence in the recovery, and open communication was maintained with families to enhance home care practices. Guidance on daily living was provided, such as advising patients and their families on the importance of a low-fat, low-salt, and low-cholesterol diet, avoiding spicy or irritating foods, maintaining a regular sleep schedule, ensuring good indoor air quality, and avoiding exposure to strong odors.

Based on conventional care, the intervention group received EBN intervention. Specifically, the following steps were taken: First, an EBN team was established. Before taking up their positions, team members were required to undergo training and assessment to ensure they possessed strong work capabilities, a sense of responsibility, rich experience, and a comprehensive grasp of relevant knowledge. They also received regular training on the principles and concepts of evidence-based nursing and were involved in formulating nursing plans. Additionally, potential challenges that patients with MI undergoing PCI and confirmed postoperative reperfusion injury might encounter during the nursing intervention process were identified. Databases, journals, and professional websites were utilized to retrieve research findings related to these issues, including clinical studies, expert consensus, and conference records, while the credibility of the information was screened. The quality of the materials was assessed, with attention paid to the design rationale, sample size, feasibility of interventions, and the credibility of outcomes. Only rigorously evaluated materials were used as the basis for developing nursing plans. Meanwhile, nursing plans, where nursing staff were formulated; based on the retrieved findings and their own clinical observations of patients with MI undergoing PCI and experiencing reperfusion injury, along with the individual circumstances of the patients, nursing staff selected the most appropriate nursing plan. The nursing plans were first self-evaluated within the team. Subsequently, meetings were organized with healthcare professionals who had extensive clinical experience to evaluate the aforementioned plans, ensuring the rationality and effectiveness of the nursing content. This was then incorporated into the training to strengthen the team members’ understanding and was subsequently applied in clinical practice. Furthermore, the nursing plan was implemented; during this process, the patient’s responses were recorded to provide experimental data for subsequent research. In addition, the nursing outcomes were evaluated; the plan was optimized based on whether the expected results were achieved. The plan was also continuously improved; nursing staff constantly stayed updated on the latest nursing knowledge to enhance their professional competence and nursing standards.

We employed echocardiography to assess the cardiac function indicators, specifically the left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDD), before and after the intervention. LVEF was calculated using the formula: LVEF = (end-diastolic volume (EDV) - end-systolic volume (ESV))/EDV × 100%. The measurement of LVEDD was conducted utilizing the principle of ultrasound reflection to generate images of the heart. A professional physician acquired images of the left ventricle from the parasternal long-axis view and measured the LVEDD.

We collected 5 mL of fasting peripheral venous blood from patients in the morning to measure the levels of cardiac injury markers, including N-terminal pro-brain natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI). The measurements were performed using a Beckman Coulter immunoassay analyzer (model: Dxl 800/Access 2, purchased from Beckman Coulter), strictly adhering to the step-by-step instructions outlined in the user manual. The cut-off value for NT-proBNP is set at 300 pg/mL; the normal range for cTnI is 0–0.3 ng/mL.

To evaluate changes in patients’ psychological states before and after the intervention, we utilized the Self-Rating Anxiety Scale (SAS) and the Self-Rating Depression Scale (SDS). Higher scores on these scales indicated more pronounced levels of anxiety and depression in patients.

We monitored the incidence of complications, including ventricular fibrillation, vagal reflex, hypotension and acute thrombosis, over a 3-month follow-up period. During this time, we also recorded any cases of sudden death. Nursing satisfaction was assessed using a custom-designed questionnaire from our hospital, with a total of 20 items, each with five points, for a total of 100 points. A score of ≥80 points was highly satisfied, 60–80 points was satisfied, and <60 points was dissatisfied. The satisfaction rate was calculated as (highly satisfied + satisfied)/total cases × 100%. The pre-experimental exhibited a content validity of 0.73, and Cronbach’s α coefficient stood at 0.85.

Statistical analysis was carried out using SPSS 22.2 and GraphPad 10.0. Data that followed a normal distribution were presented as mean ± standard deviation (x ± s). Independent sample t-tests were used for comparisons between groups, while paired sample t-tests were applied for comparisons before and after interventions. Categorical data were expressed as percentages (%), and the χ² test or Fisher’s exact test was utilized for inter-group comparisons. A P-value of less than 0.05 was considered statistically significant.

Ninety eligible patients were randomly divided into two groups: the intervention group and the control group, with 45 cases in each group. The intervention group comprised 29 males and 16 females, aged 43–65 years, with an average age of 53.69 ± 6.65 years. The control group included 28 males and 17 females, aged 42–66 years, with an average age of 55.84 ± 6.60 years. No significant differences were observed in the baseline characteristics between the two groups (P > 0.05), ensuring the comparability of the study results.

Before the intervention, there were no significant differences in LVEF and LVEDD measurements between the two groups (P > 0.05). Following the intervention, both groups showed a significant increase in LVEF and a significant decrease in LVEDD compared to pre-intervention levels (P < 0.05). Additionally, the intervention group exhibited better LVEF and LVEDD outcomes than the control group (t = 12.550, 10.150, P < 0.05) (Table 1; Figure 1).

Prior to the intervention, no significant differences were observed in NT-proBNP and cTnI levels between the two groups (P > 0.05). Post-intervention, both groups demonstrated a significant reduction in NT-proBNP and cTnI levels compared to baseline (P < 0.05). Furthermore, the intervention group had lower NT-proBNP and cTnI levels than the control group (t = 16.396, 4.759, P < 0.05) (Table 2; Figure 2).

Before the intervention, there were no significant differences in SAS and SDS scores between the two groups (P > 0.05). After the intervention, both groups showed a decrease in SAS and SDS scores compared to pre-intervention levels (P < 0.05). The intervention group had significantly lower SAS and SDS scores than the control group (t = 12.218, 7.336, P < 0.05) (Table 3; Figure 3).

The intervention group had significantly lower rates of complications (χ² = 5.120) and sudden death compared to the control group (P < 0.05) (Table 4).

Patients in the intervention group reported significantly higher satisfaction levels with nursing care compared to those in the control group (P < 0.05) (Table 5).