Sequence generation and concealment mechanism.

In this study, stratified block randomization was employed, divided into 10 tiers according to the study center, with 20 patients in each group, to ensure a balanced number of cases between groups. Within the stratum, participants were divided into two groups using a randomized 1:1 ratio, participants will be allocated into either of two groups: the cardiovascular ultrasound therapy group and the control group. This process will be facilitated by a computer-generated randomization sequence. To uphold the integrity of the allocation process, a team of research assistants not involved in clinical care or outcome assessment will meticulously craft sequentially numbered, opaque, sealed envelopes based on the predefined randomization list. This meticulous approach will ensure the safeguarding of confidentiality and the autonomy of allocation data. When appropriate, the assistants will open envelopes and ensure the coordination of therapeutic interventions.

To ensure the reliability and accuracy of the study results, we use blinding, the assignment results will be concealed from the attending physicians, the patients and the investigative team members responsible for the collection of primary outcome data will remain masked. Consequently, the study design adheres to the framework of a blinded controlled trial. Patients will retain the prerogative to decline study participation, in which case they would receive standard care only.

Who will take informed consent?

The research assistants (CHs) will take informed consent before trial baseline evaluation in the participants’ reception room. Participants will be told why the study is being conducted, what they will be doing, and the possible benefits and risks. If participants have any questions, they will be free to ask them. Then, being fully informed, they will be able to decide whether or not to participate in the study.

Additional consent provisions for the collection and use of participant data and biological specimens.

No additional biological samples have been collected for the study. No subject data are currently available for future studies. Additional consent from participants will be obtained if relevant data should be required for future studies.

Explanation for the choice of comparators.

We intend to select the prevailing standard (sham stimulating) allopathic therapy as the control condition to determine if the expected benefits of cardiovascular ultrasound therapy will produce better anti-inflammatory results than standard therapy.

Intervention description.

Before treatment, all participants will attend a comprehensive health education class conducted by a research assistant and lasting for about 20 minutes. It would include essential topics such as CAD, risk factors, clinical manifestations, treatment interventions, and a detailed discussion of the evidence-based efficacy and safety aspects of cardiovascular ultrasound therapy. Moreover, patients will be advised to adhere to a light diet, refrain from smoking and excessive alcohol consumption, engage in moderate physical activity, maintain regular medical checkups, and diligently follow the recommendations of their healthcare providers.

Participants allocated to the intervention group will undergo a 14-day regimen utilizing a medical cardiovascular ultrasound therapy device (838C-M-L-I/II, Shenzhen, China). The ultrasound instrument is equipped with a sound head comprising five transducer units operating at an ultrasonic frequency of 0.84 MHz with a sound intensity range of 1 W/cm²–1.25 W/cm². The therapeutic ultrasound sessions require a controlled environmental temperature. Patients will assume the supine position, exposing the precordial region, with the 5-pronged head positioned parallel to the heart’s long axis; it should cover the entire precordial region including the right and left coronary arterial trunks and the aortic root. The five transducer units function sequentially in a scanning pattern, with each unit operating for 5 seconds and transitioning with a 0.5-second interval, following a clockwise rotation until the treatment has been completed. The cardiovascular ultrasound therapy device operates in a pulsed mode, and each treatment session lasts for 20 minutes; there would be two daily sessions for a total of 20 treatments.

Participants in the control group will not receive a real treatment with cardiovascular ultrasound therapy, but will be treated with a simulator (sham stimulating). Cardiovascular ultrasound therapy will be assessed at baseline (24th-hour post-PCI), on the 14th day, and at the end of the first and third months post-intervention.

Criteria for discontinuing or modifying allocated interventions.

Upon request and at any point, patients are free to withdraw from participation without adverse consequences, and thereafter their data would neither be collected nor utilized for analysis. Cardiovascular ultrasound therapy is a safe treatment modality that has been approved by the China Food and Drug Administration. To date, no serious adverse events have been reported with the use of cardiovascular ultrasound therapy for cardiovascular disease. Nevertheless, our nursing staff will vigilantly monitor possible mild reactions such as local swelling, minor bleeding, heightened local pain sensations, and local hyperesthesia or reduced sensitivity. If such reactions should occur, treatment will be administered promptly. Participants may discontinue their involvement in the study should they encounter adverse events that they find unacceptable.

Strategies to improve adherence to interventions.

To promote adherence to the interventions, free measures (including vascular endothelial function testing, hemodynamic monitoring, the 6-minute walk test [6MWT], HRV testing, recording of symptoms, and scoring of depression and anxiety) will be offered following treatment. We will also be offering financial incentives or free post-study services to encourage continued participation. Additionally, implementing strategies like follow-up phone calls or sending regular reminders could promote long-term adherence to the study’s timeline.

Relevant concomitant care permitted or prohibited during the trial.

All participants will receive routine treatment but no additional cardiac or other rehabilitation.

Provisions for posttrial care.

The trial interventions have been meticulously designed to ensure minimal to no harm to participants. However, should a participant sustain an injury during the trial, we would promptly assess, document, and treat the injury while also covering all associated medical expenses.

Primary outcome.

The primary outcome measures will be the levels of hsCRP in the peripheral serum following 20 cardiovascular ultrasound therapy sessions. Comparative analyses will be conducted between the cardiovascular ultrasound therapy intervention and control groups along with pre- and postintervention assessments.

Secondary outcome.

Indicators of serum myocardial injury and blood lipid levels: Serum biomarkers indicative of myocardial injury encompass creatine kinase isoenzymes (CK-MB), cardiac troponin I (c-TnI), and myeloperoxidase (MPO). Lipid profile markers in serum comprise total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), apolipoprotein A (ApoA), apolipoprotein B (ApoB), lipoprotein (a), and oxidized low-density lipoprotein (ox-LDL) in the peripheral blood.

Monitoring of serum biomarkers indicative of myocardial injury will be conducted at baseline (24th hour post PCI), on the 14th day, and at the end of the 1st and 3rd months post intervention.

Serum markers of endothelial function: The serum markers utilized to assess endothelial function encompass endothelial nitric oxide synthase (eNOS), endothelin-1 (ET-1), and vascular endothelial growth factor (VEGF) in the peripheral blood.

Monitoring of serum endothelial function will be conducted at baseline (24th hour post PCI); on the 7th and 14th days; and at the end of the 1st and 3rd months post intervention.

Serum inflammatory factors: Each morning, 5 mL of fasting venous blood will be drawn by nursing staff to assess the proportion of inflammatory cells and measure levels of inflammatory markers in the peripheral blood.

Monitoring of serum inflammatory factors will be conducted at baseline (24th hour post PCI), on the 14th day, and at the end of the 1st and 3rd months post intervention.

Hemodynamic parameters: These encompass a comprehensive range of indicators, including cardiac index (CI), cardiac output (CO), stroke volume (SV), stroke volume index (SVI), mean arterial pressure (MAP), stroke systemic vascular resistance index (SSVRI), left ventricular stroke work index (LVSWI), systemic vascular resistance index (SVRI), ejection phase contraction index (EPCI), inotropic state index (ISI), systemic vascular resistance (SVR), vascular resistance (VR), and mean heart rate (mHR).

Certified sonographers will monitor hemodynamic parameters at baseline (24th hour post PCI); on the 7th and 14th days; and at the end of the 1st and 3rd months post intervention.

Echocardiography: The echocardiogram parameters will encompass E/e’ ratio, left ventricular ejection fraction (LVEF), and wall thickening fraction (WTF). WTF is defined as [(end-diastolic wall thickness − end-systolic wall thickness)/ end-diastolic wall thickness] × 100 (%).

Echocardiographic assessments will be conducted by certified sonographers proficient in thoracic echocardiography. This will be done at multiple time points: at baseline (24th hour post PCI), on the 7th and 14th days, and at the end of the 1st and 3rd months post intervention.

Ultrasound examination of carotid plaques: Ultrasonography of carotid plaques includes their location, size (length x width), and morphology as well as the intima-media thickness (IMT) and Crouse’s score of the common carotid artery. IMT was measured at 1.5 cm from the origin, branch, trunk, and bifurcation of the common carotid artery bilaterally. During plaque examination, plaque thickness was recorded and Crouse’s score was calculated by adding the thickness of each plaque. Common carotid artery hemodynamic indexes, including the peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) of the common carotid artery were detected.

A certified sonographer proficient in examining the carotid arteries will perform ultrasound evaluations at multiple time points: at baseline (24th hour post PCI); on the 7th and 14th days; and at the end of the 1st and 3rd months post intervention.

Six-minute walk test: The 6MWT quantifies the maximal distance an individual can walk in 6 minutes, serving as an indicator of the patient’s exercise capacity and cardiorespiratory fitness during routine physical activities.

A certified cardiologist will conduct the 6MWT at various time points, including at enrollment, on the14th day, and at the end of the 1st and 3rd months post intervention.

Short-term heart rate variability: HRV refers to the fluctuation in the timing of consecutive heartbeats or the variance in heart rate. It is determined by the duration between two successive R-R intervals, representing the slight deviation between each cardiac cycle. HRV assessment will be conducted using the multiparameter monitor (WMMS201, Beijing, China). With the patient at rest and in a supine position, short-term (5-minute) HRV will be measured during daytime hours [19].

Certified cardiologists will perform short-term HRV assessments at baseline (24th hour post PCI), on the 7th and 14th days, and at the end of the 1st and 3rd months post intervention.

Tools for mental health assessment: The Patient Health Questionnaire-9 (PHQ-9) is a critical instrument for the screening, diagnosis, and assessment of depression, enabling the measurement of its severity (S1 Table). Concurrently, the 7-item Generalized Anxiety Disorder Scale (GAD-7) enables the evaluation of generalized anxiety disorder (S2 Table). Similarly, the Pittsburgh Sleep Quality Index (PSQI) stands as a widely recognized assessment tool for determining sleep quality (S3 Table), and the Seattle Angina Questionnaire (SAQ) functions as a self-administered assessment tool designed to evaluate specific functional status and quality of life among individuals with CAD (S4 Table).

Mental health assessments will be conducted by certified psychologists at various time points: at baseline (24th hour post PCI), on the 14th day, and at the end of the 1st and 3rd months post intervention.

Participant timeline: This study is scheduled to begin in 2025. The participant timeline is shown in Fig 1.

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Fig 1. SPIRIT schedule of enrolment, interventions, and follow-up of the study.

The specific time points are listed in the columns and the events are given in the rows. Participants will be randomly allocated to Routine treatment (x¹) or Routine treatment with cardiovascular ultrasound therapy (x²). All participants will have a follow-up visit at 1 months, 3 months. D, day; M, month. Tools for mental health assessment would include recording and scoring the patient’s Health Questionnaire-9, 7-item Generalized Anxiety Disorder Scale, Pittsburgh Sleep Quality Index, and Seattle Angina Questionnaire.

https://doi.org/10.1371/journal.pone.0327557.g001

Plans for assessment and collection of outcomes.

The primary outcome data will be captured both at the baseline and the conclusion of treatment (20th time); the secondary outcome data will be gathered during the baseline assessment (24th hour post PCI); on the 7th and 14th days; and at the end of the 1st and 3rd months post intervention. Every variable outlined in the protocol will be meticulously documented within an encrypted Microsoft Office Excel spreadsheet. The investigators entering the data into the spreadsheet will be responsible for ensuring the accuracy and comprehensiveness of all the information. A day-to-day management group comprising the principal investigator, a doctoral student, a research coordinator, and an assistant manager will oversee these procedures.

Plans to promote participant retention and completion of follow‑up.

All evaluations and treatments will be conducted during the patients’ hospital stay. Results regarding vascular endothelial function, hemodynamic monitoring, HRV, 6MWTs, and any trial-related score administered before or after treatment will be offered to the patients at no cost. If a patient opts to withdraw from the study prematurely (within the 14-day treatment period), their data will not be included in the final analysis. Maintaining patient engagement throughout the planned outcome assessments is crucial, and every effort should be made to promote patient retention for the entire 14 days.

Data management.

Initially, investigators will collect data on participants’ baseline status; then, after randomization, data will be collected daily. All acquired data will be securely stored electronically in a confidential database with restricted access. To ensure security, the transfer process will include encryption, and any personally identifiable information will be expunged. Reversal of the encryption (i.e., identification of the data) will be permitted only during the concluding phase of the trial. Participants who choose not to continue or are found to meet any of the exclusion criteria will be withdrawn from the study. The suspension details, including the date and reason, will be documented and the participants’ data will not be retained.

Confidentiality.

Each participant’s data will be given a unique identifier and securely stored on a dedicated server accessible only to authorized researchers with administrative privileges. After the trial, only data without personal information will remain accessible.

Determination of primary and secondary outcomes.

The baseline characteristics of both groups will be summarized using appropriate descriptive statistics. Analysis of both primary and secondary outcomes will be based on the intention-to-treat approach, ensuring that all participants remain assigned to their original group throughout the study.

Normally distributed data will be presented as the mean (standard deviation), and non–normally distributed data will be depicted as the median (interquartile range). Group comparisons will be conducted using independent sample tests, and within-group comparisons before and after treatment will be evaluated using paired sample tests. Clinical symptom variables will be portrayed as percentages. Categorical data will be assessed using either the chi-squared test or Fisher’s exact test. A significance level of.05 will be employed to interpret the P values. The statistical analysis will be conducted utilizing SPSS version 26 statistical software (IBM, Armonk, NY).

Interim analyses.

No interim analyses are being planned.

Methods for additional analyses (e.g., subgroup analyses).

No subgroup analyses will be conducted.

Analytic methods for handling protocol nonadherence and statistical methods for handling missing data.

We anticipate minimal missing data (<10%) for the primary outcome given that all participants will be in patients with regular daily contact maintained during treatment. The evaluation of missing data effects will involve comparing differences under plausible and extreme missing data scenarios. In the event of a significant primary test result, we will also assess the interaction size between group assignment and missing data necessary to render the difference nonsignificant. Should 10% or more of the baseline samples be excluded due to missing data, we will apply multiple imputation techniques for comprehensive analysis.

Plans to give access to the full protocol, participant‑level data, and statistical code.

Anonymized participant data can be made available upon a reasonable request from the corresponding author. However, there are no plans to provide public access to participant data or the statistical code.

Oversight and monitoring.

Composition of the coordinating center and trial steering committee: Ongoing clinical monitoring will be overseen by a day-to-day management team comprising the principal investigator (PI), a doctoral student, a research coordinator, and an assistant manager. Regular weekly meetings will be held by the group to ensure effective coordination and management of the study. This trial does not have a trial steering committee.

Composition of the data monitoring committee—Its role and reporting structure: We will establish a formal data monitoring committee composed of experts in the cardiovascular field, statistical analysis and ethics to regularly review the data to ensure quality, independently determine adverse events and supervise rectification to ensure the integrity and accuracy of the data.

Adverse events reporting and harms: All adverse events, defined as any unfavorable or unintended reactions to the intervention, will be meticulously documented based on patient-reported symptoms and observational assessments during each visit. To date, no adverse events have been reported with use of the cardiovascular ultrasound therapy regimen in cardiovascular disease. Potential mild adverse reactions—including mild local swelling, heightened local pain response, and altered local sensitivity—will be monitored closely. In the event of such symptoms, prompt and suitable symptomatic treatment will be administered.

Frequency and plans for auditing trial conduct: Not applicable. No auditing is planned in this trial. The PI will meet weekly during the study period to review trial progress.

Plans for communicating important protocol amendments to relevant parties (e.g., trial participants, ethical committees): Any proposed modifications to the study protocol require prior approval from the Ethics Committee of Qilu Hospital of Shandong University. Upon approval, these protocol amendments must be documented in the trial register and, for transparency and accuracy, integrated into the final research report.

Dissemination plans: The outcomes of the clinical trial are intended for dissemination through publication in medical journals and presentations at national and international conferences. The lead and corresponding authors will be responsible for overseeing this process.