Abstract Body (Do not enter title and authors here): Background
Coronary artery calcium (CAC) scoring is a key tool for risk stratification in preventive cardiology. While clinician-referred patients are typically higher-risk, some institutions adopted low-cost promotional CAC screening to enable risk assessment in individuals not reached by traditional referrals.

Research question
Among a diverse, urban cohort, do comorbidities, baseline preventive therapy, and CAC scores differ between patients undergoing clinician-referred vs. promotional CAC screening?

Methods
A retrospective cohort study was conducted at a large urban academic center in Chicago. Adults undergoing CAC screening from Jan 2022 to Dec 2023 via clinician referral or low-cost promotion were included. The primary exposure was referral pathway. The primary outcome was CAC burden, categorized by Agatston score (0 = none, 1–99 = mild, 100–299 = moderate, ≥300 = severe) and stratified by coronary artery territory (Left Main, LAD, LCX, RCA). Baseline comorbidities and use of preventive medications were recorded. Descriptive statistics compared baseline characteristics. CAC coronary distributions were assessed using chi-square tests.

Results
1,743 patients were screened, 932 via clinical referral and 811 through promotion. Compared to referral patients, promotion patients had lower rates of HTN (26.1% vs. 38.4%, p<0.001), dyslipidemia (15.9% vs. 24.7%, p<0.001), and CAD (6.3% vs. 11.4%, p<0.001). Preventative medication use was lower in the promotion group: any statin (41.3% vs. 51.1%, p<0.001), high-intensity statin (14.9% vs. 24.4%, p<0.001), moderate-intensity statin (33.7% vs. 39.8%, p=0.008), aspirin (29.7% vs. 38.0%, p<0.001), and ezetimibe (2.0% vs. 4.6%, p=0.002).

Referral patients had higher rates of overall Left Main(17.5% vs. 10.8%, p<0.001) and LCX (25.6% vs.23.5%, p=0.044) CAC burden. LAD(42.2% vs. 46.9%, p=0.113) and RCA(27% vs. 28.6%, p=0.433) CAC burdens did not differ significantly between promotion and referral groups moderate/severe total CAC prevalence was similar between the promotion and referral cohorts(22.4% vs.25.7%, p=0.098).

Discussion
Promotion patients showed a high prevalence of non-zero CAC and similar moderate/severe CAC burden as referred patients, despite fewer comorbidities and lower medication use. These findings support low-cost promotional CAC screening as a practical method for detecting subclinical atherosclerosis and may enhance early risk detection in asymptomatic patients not typically reached by clinician referral.