Atrial fibrillation is considered a relative contraindication to coronary computed tomographic angiography (CCTA) because image quality and radiation dose-saving measures largely depend on low and stable heart rates. Most published experiences with CCTA during atrial fibrillation have relied on retrospective gating to mitigate artifacts via electrocardiogram editing. However, a large number of patients arrive at the CT suite with irregular heart rates. We present a case in which we used a prospectively electrocardiogram-triggered axial-sequential scan mode with a novel arrhythmia protection algorithm to obtain motion-free, high-quality CCTA images at a low radiation dose.