Rationale and design of the Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography IMaging (PARADIGM) registry: A comprehensive exploration of plaque progression and its impact on clinical outcomes from a multicenter serial coronary computed tomographic angiography study

The natural history of coronary artery disease (CAD) in patients with low-to-intermediate risk is not well characterized. Although earlier invasive serial studies have documented the progression of atherosclerotic burden, most were focused on high-risk patients only. The PARADIGM registry is a large, prospective, multinational dynamic observational registry of patients undergoing serial coronary computed tomographic angiography (CCTA). The primary aim of PARADIGM is to characterize the natural history of CAD in relation to clinical and laboratory data. Design The PARADIGM registry (ClinicalTrials.gov NCT02803411) comprises ≥2,000 consecutive patients across 9 cluster sites in 7 countries. PARADIGM sites were chosen on the basis of adequate CCTA volume, site CCTA proficiency, local demographic characteristics, and medical facilities to ensure a broad-based sample of patients. Patients referred for clinically indicated CCTA will be followed up and enrolled if they had a second CCTA scan. Patients will also be followed up beyond serial CCTA performance to identify adverse CAD events that include cardiac and noncardiac death, myocardial infarction, unstable angina, target vessel revascularization, and CAD-related hospitalization. Summary The results derived from the PARADIGM registry are anticipated to add incremental insight into the changes in CCTA findings in accordance with the progression or regression of CAD that confer prognostic value beyond demographic and clinical characteristics.