Clinical Features, Current Treatment and Clinical Outcomes in Patients With INR-CAD: a Cohort Study

A special type of coronary artery disease (CAD) has been identified in our clinical practice. The patients have significantly different clinical features from those of typical atherosclerotic coronary artery disease (AS-CAD), including: 1) predominantly female; 2) early onset CAD; 3) lack of traditional atherosclerotic risk factors; 4) often with evidence of chronic inflammation; 5) responding poorly to intensified secondary prevention and optimized coronary revascularization (percutaneous coronary intervention [PCI] or coronary bypass graft [CABG]); 6) delayed disease progression on immunosuppressive therapy. This special type of CAD is named with inflammation-associated coronary artery disease (I-CAD). Currently, the pathogenesis as well as the optimal approach regarding the diagnosis and treatment of I-CAD remain unknown.

Based on the rate of disease progression and the urgency for clinical management, I-CAD is classified into two categories: 1) inflammation-associated rapidly-progressive coronary artery disease (IR-CAD), which is defined as I-CAD with progression of coronary de novo and/or restenotic lesions within 6 months or within 12 months (only for patients receiving immunosuppressive therapy within 24 months); 2) inflammation-associated non-rapidly-progressive coronary artery disease (INR-CAD), which is defined as I-CAD not fulfilling the criteria for IR-CAD.

It has been recognized in our clinical practice that INR-CAD is a highly heterogeneous group of diseases. Therefore, the present observational cohort study was designed to investigate the clinical features, current treatment and clinical outcomes in patients with INR-CAD.

All patients who have been admitted to the Department of Cardiology, Peking Union Medical College Hospital (PUMCH) since January 1, 2022 will be screened for study participation. Clinical diagnostic criteria and a clinical follow-up protocol have been specifically designed for INR-CAD in our center. Patients are clinically diagnosed as INR-CAD if they 1) have angiographic evidence of coronary lesions (de novo or restenotic); 2) have evidence of chronic inflammation (positive inflammatory markers or positive autoantibodies or established diagnosis of chronic inflammatory diseases or use of immunosuppressive therapy) within 24 months; 3) not meet the clinical diagnostic criteria for IR-CAD. Once the clinical diagnosis is established, INR-CAD patients will receive a 24-month clinical follow-up according to the clinical follow-up protocol for INR-CAD in PUMCH. Patients who have been clinically diagnosed as INR-CAD and received, or are receiving, or will receive the 24-month clinical follow-up will be enrolled in the present cohort study.

The primary efficacy endpoint is major adverse cardiovascular events (MACE). The secondary efficacy endpoints include the individual components of MACE, exercise capacity, angiographic metrics of coronary lesions, and inflammatory markers. The safety endpoints are major bleeding events and severe infection events.

For the endpoints which are categorical variables, e.g., MACE, the event rate for the first occurrence of each endpoint during the 24-month clinical follow-up will be calculated. Chi-square test or Fisher's exact test will be used to compare the event rate for each endpoint between patients with different diagnosis and/or those receiving different treatment, including patients 1) with vs. without established diagnosis of chronic inflammatory diseases; 2) receiving vs. not receiving immunosuppressive therapy; 3) receiving vs. not receiving coronary revascularization.

For the endpoints which are continuous variables, e.g., inflammatory markers, 1) paired t-test or paired rank sum test will be used to compare the level of each endpoint at the end of the 24-month clinical follow-up with that at baseline (the diagnosis of INR-CAD); 2) analysis of co-variance (ANCOVA) will be used to compare the level of each endpoint at the end of the 24-month clinical follow-up between patients with different diagnosis and/or those receiving different treatment, including patients ① with vs. without established diagnosis of chronic inflammatory diseases; ② receiving vs. not receiving immunosuppressive therapy; ③ receiving vs. not receiving coronary revascularization.