To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol. 100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated. Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P < 0.001). Effective dose was 4.29 +/- 1.86 and 11.95 +/- 5.34 mSv for each of the two protocols (P < 0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging. In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease > 60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality. aEuro cent Coronary computed tomographic angiography (CCTA) can be difficult in patients with arrhythmias. aEuro cent Prospectively ECG-triggered sequential CCTA is feasible in patients with atrial fibrillation. aEuro cent Prospective sequential imaging can improve quality compared with retrospective analysis. aEuro cent Prospective sequential imaging decreases radiation exposure by 64 % compared with retrospective mode.