Objectives:
This study aimed tTo investigate the differences in coronary artery calcium scores (CACS) measured from low-dose chest CT (chest LDCT) images compared to standard ECG-gated cardiac CT（cardiac CT）images, as well as the correlation between these differences and heart rate.o investigate the differences in coronary artery calcium scores (CACS) measured from low-dose chest CT (chest LDCT) images compared to standard ECG-gated cardiac CT images, as well as the correlation between these differences and heart rate.

Methods and Materials:
Prospectively enrolled were 312 patients presenting with chest painA total of 312 patients presenting with chest pain were prospectively recruited.each undergoing a non-contrast cardiac CT and an additional chest LDCT prior to itEach patient underwent an additional chest LDCT prior to the required non-contrastECG-gatedcardiac CT. Chest LDCT images were reconstructed using both “STND” and “LUNG” kernels.Artificial intelligence-based software calculated Agatston,Volume, andMass scores across four coronary branches and the total in both modalities. The coronary artery calcium scores, including the Agatston score, Volume score, and Mass score for four coronary branches and the total, were computed using artificial intelligence-based software.Patients weredivided intocategorized into low heart rate (HR < 65 BPM) and high heart rate groups (HR ≥ 65 BPM).The differences in CACS between LDCT and cardiac CT at varying heart rates were analyzed, with linear regression assessing correlations between CACS bias and heart rateThe differences in CACS obtained from chest LDCT and cardiac CT at varying heart rates were compared. Linear regression analysis was employed to assess the correlation between the bias of CACS measured by chest LDCT and cardiac CT and heart rate. A confusion matrix was used to evaluate the performance of chest LDCT in Agatston CACS classification across different heart rate groups.

 A confusion matrix was used to evaluate the performance of chest LDCT in Agatston CACS classification across different heart rate groups.

Results:
The mean effective radiation dose was1.12±0.29mSv[!!]. For LUNG kernel reconstructions, LDCT versus cardiac CT demonstrated significant CACSdifferences inXX3 (low-HR) andXX9 (high-HR) parameters, compared toXX11 andXX14 for STND kernel. HR showed a statistically significant correlation with Volume CACS bias only in STND reconstructions(R²= 0.032[value], P= [value0.01]). Agatston and Mass CACS bias exhibited no HR-related associations (P>0.05). Agatston CACS risk stratification achieved >80% accuracy in both HR groups (low vs. high: 80% vs. 83% for STND; 84% vs. 82% for LUNG).

Conclusions:
Heart rateHeart rate does not affect the measurement accuracy of coronary artery calcium scores derived from low-dose chest CT. Both heart rate groups exhibited high accuracy in Agatston risk stratification.This suggests that cardiovascular disease risk can be simultaneously screened during low-dose CT lung cancer screening in patients with different heart rates.