Optimising the workflow of coronary computed tomography angiography through effective timing and heart rate management.

This study aims to evaluate the variations in image quality of CCTA conducted at different time intervals and their clinical implications. A retrospective analysis of 641 patients who underwent CCTA between July 2023 and June 2024 was performed. The examination times were divided into morning group(8:00-12:00, 316 cases), and afternoon group༈14:00-18:00, 325 cases) for comparison. For patients with a heart rate ≥ 60 bpm, 25 mg of metoprolol was given orally to control heart rate, along with 0.5 mg of sublingual nitroglycerin before the CCTA examination. Image quality, initial heart rate, post-medication heart rate, heart rate differences (pre- and post-medication), percentage heart rate changes, radiation dose, age, and sex were compared between the two groups. Statistical analyses, including the Mann-Whitney U test, Spearman correlation coefficients, and logistic multivariate regression, were used to assess factors influencing image quality. Finally, receiver operating characteristic (ROC) curves were used to analyse the predictive value of examination timing on image quality. The image quality excellence rates for the morning group and the afternoon group were 87.9% and 74.1%, respectively, with no undiagnosable cases in either group. Significant differences (P < 0.05) were observed between the two groups in subjective image scores, post-medication heart rates, heart rate differences (pre- and post-medication), percentage heart rate changes, and age. However, no significant differences were found in initial heart rate, radiation dose, or sex (P > 0.05). Logistic multivariate regression analysis indicated a statistically significant association between image quality and both examination timing and age (P < 0.05). However, no significant associations were found with initial heart rate, heart rate differences (pre- and post-medication), percentage heart rate changes, radiation dose, or sex (P > 0.05). The regression equation was determined as Y = 11.386 + 0.873 × 1 + 0.023 × 2, where Y represents image quality, X1 represents the examination timing, and X2 represents age. For the morning group, the ROC curve area under the curve (AUC) for initial heart rate and post-medication heart rate were 0.598 and 0.890, with optimal thresholds of 79 bpm and 71 bpm, respectively. For the afternoon group, the AUC values were 0.596 and 0.812, with optimal thresholds of 75 bpm and 68 bpm, respectively. CCTA performed in the morning (8:00-12:00) yields superior image quality compared to the afternoon (14:00-18:00). Moreover, morning CCTA scans tolerated higher initial heart rates (up to 79 bpm) without affecting image quality, in contrast to the lower threshold of 75 bpm in the afternoon. These findings offer robust data to guide the timing of clinical CCTA procedures and heart rate management, indicating that morning CCTA scans may facilitate higher-quality imaging, especially for patients with elevated heart rates.