Background: Prospectively electrocardiography (ECG)-triggered high-pitch spiral coronary computed tomography angiography (CCTA) is a unique scan mode for dual-source CT (DSCT). Our reports aim to compare image quality and radiation dose of CCTA using high-pitch spiral or sequential acquisition mode in patients with low and stable heart rates. Materials and Methods: Patients with low and stable heart rates (HR) (HR ≤ 70 beats per minute [bpm]; heart rate variability [HRV] < 10 bpm) were randomly assigned to high-pitch spiral mode (group A; n = 80) or sequential acquisition mode (group B; n = 80). Image quality scores, image noise, effective radiation dose and influencing factors on image quality were assessed.  Results: Mean image quality scores were 1.51 ± 0.32 and 1.70 ± 0.38 for groups A and B (P < 0.05), respectively. Image noises of the two groups were 19.05±4.70 Hu and 27.21±8.88 Hu (P < 0.05). Contrast media cost in group A was lower than group B (P < 0.05). No statistical difference was found in the rate of diagnostic patients between the two groups (P = 0.416). The estimated radiation dose of group A was 26.0% reduced compared with group B (0.74 ± 0.34 mSv vs. 1.00 ± 0.48 mSv, P < 0.05). Conclusion: In patients with regular and low heart rates, the prospectively high-pitch spiral acquisition mode can reduce radiation dose and contrast media cost while maintaining image quality compared with the prospectively sequential mode.