The main goal of this clinical trial is to evaluate the feasibility of conducting a large-scale clinical trial testing a program containing several aspects for reducing the effects of air pollution on cardiovascular health (which is named the hybrid program hereafter) in adult patients (18 years or older) with atherosclerotic cardiovascular disease. Furthermore, we seek to answer how much patients adhere to and are satisfied with implementing the hybrid program, and what problems executing this program will bring for patients.

Background:

Air pollution, as the fourth leading cause of mortality globally, is annually responsible for 6.67 million deaths worldwide and approximately half of them are attributable to cardiovascular causes. Some of the pollutants can negatively affect the cardiovascular system, as they may pass through the lungs, entering into the bloodstream, and cause inflammation and oxidative stress. Exposure to these pollutants is associated with a diverse range of fatal and/or adverse non-fatal cardiovascular events, including myocardial infarction, heart failure, atrial fibrillation, and ischemic stroke.

Besides strategies in societal-level aiming to control the air pollution, various individual-level solutions have been suggested to mitigate the health-related effects of air pollution. Text messaging via mobile phones to alert individuals about unhealthy air quality levels, and recommending to limit activity and time spent in outdoors, use face mask when going out, or use air filtration systems are among these individual-level solutions to restrict the air pollution-related health effects. Furthermore, several studies have proposed dietary interventions and demonstrated that some nutrients, especially vitamins C and E, are potentially capable to counter with the adverse effects of air pollutants on the cardiovascular system. However, the efficacy of these individual-level solutions to reduce the the incidence of clinically relevant outcomes such as myocardial infarction, stroke, and acute limb events.

The current pilot randomized controlled trial (RCT) seeks to test the feasibility and adherence of patients with atherosclerotic cardiovascular diseases (ASCVD) to a multifaceted intervention including a one-page informational flashcard, cell phone message alerting on days with poor air quality to encourage patients not to spend time outdoors, or to wearing KN-95 facemasks outdoors in those days, and encouraging patients to consume citrus fruits on highly polluted days (which is hereafter referred to as hybrid strategy).

Randomization Procedure:

Single-center (Rajaie Cardiovascular Medical and Research Center) open-label randomized controlled trial with a 1:1 allocation ratio to hybrid strategy versus control. Permuted block randomization with block sizes of four via a web-based system will be used for the study. The specifications for the generation of the randomization schedule will be prepared by the study biostatistician. For this study, the randomization schedule refers to a list that includes the subject identification number, randomization block number, randomization code, and the allocated treatment. Such data will be kept confidential and not shared with clinical coordinators, the Steering Committee, or other trial staff members.

Outcome assessment:

The outcomes will be adjudicated by the Steering Committee, blinded to the assigned intervention

Statistical Considerations:

A convenience sample size of 50 patients (25 in the intervention arm and 25 in the control arm) is considered for this feasibility trial without power calculation for hypothesis testing. Categorical variables will be summarized as counts, percentages, and corresponding 95% confidence intervals, and will be compared between intervention and control arms using the chi-squared test. Normally distributed continuous variables will be presented as mean ± standard deviation and will be compared using the independent samples T-test. Non-normally distributed continuous variables will be expressed as median and interquartile range and will be compared using the Mann-Whitney U test. Hypothesis testing, if performed, will be for the purpose of hypothesis generation.

Inclusion Criteria:

• Adult patients (≥18 years) with documented ASCVD defined as at least one of the following:

  • Coronary artery disease (CAD):

    1. Previous or recent documented type I myocardial infarction
    2. History of coronary revascularization (percutaneous coronary intervention or coronary artery bypass graft surgery)
    3. History of obstructive CAD (>50% stenosis) documented by coronary computed tomography (CT) or conventional angiography

  • Peripheral arterial disease (PAD):

    1. Previous or recent acute ischemic limb event (>7 days prior)
    2. History of previous endovascular/surgical lower or upper extremities revascularization for an atherosclerotic cause
    3. History of ulcer or lower extremities amputation due to ASCVD.

  • Carotid arterial diseases:

    1. History of previous endovascular/surgical carotid artery revascularization for atherosclerotic cause
    2. History of > 50% carotid artery stenosis based on documented imaging tests (Duplex ultrasonography, CT angiography, magnetic resonance angiography, or conventional angiography)

  • Ischemic stroke:

    1. History of recent or previous documented ischemic stroke not due to systemic hypoperfusion/hypotension being treated with low-dose aspirin

• Willing to participate and able to provide written informed consent

Exclusion Criteria:

• Being within 7 days of acute/unstable ASCVD events (acute myocardial infarction, acute limb event, and acute ischemic stroke) or receiving triple antithrombotic therapy
• Active bleeding
• History of upper gastrointestinal bleeding within the past 30 days
• History of intracranial hemorrhage within the past 30 days
• End-stage kidney disease with estimated creatinine clearance < 15 mL/min, or undergoing hemodialysis or peritoneal dialysis
• Known aspirin sensitivity without prior successful desensitization
• Known comorbidities associated with poor prognosis (e.g., metastatic cancer) in conjunction with an estimated life expectancy of less than one year according to the treating clinician
• Vascular disease known exclusively to be from causes other than atherosclerosis (spontaneous coronary or peripheral dissection (fibromuscular dysplasia, segmental arterial mediolysis) or vasculitis such as Takayasu arteritis, Buerger's disease (i.e., thromboangiitis obliterans), and Churg Strauss syndrome
• Inherited or acquired severe coagulopathies including hemophilia and decompensated liver cirrhosis
• Any other unexpected/unwarranted conditions that make the participants unsuitable for recruitment or follow-up
• Known allergy to KN-95 or other masks, or citrus fruits
• Any facial dysmorphia that makes the patient unable or unwilling to wear a face mask
• Any medical condition necessitating unblinded facemask use for outdoor activities at the discretion of the treating clinician, or based on patient preference
• Inability to receive/read text messages/phone calls by personal mobile phone
• Unwillingness to participate, such as hesitation to wear a mask, if randomized