BACKGROUND Patients with atrial fibrillation (AF) are generally excluded from coronary CT angiography (CCTA) studies because of motion artifact resulting from irregular rhythm. The 83-millisecond temporal resolution of the dual-source CT (DSCT) may be sufficient to allow CCTA in patients with AF. OBJECTIVE We examined the feasibility of DSCT in patients with AF referred for CCTA. METHODS We compared results of CCTA with DSCT in 24 consecutive patients with AF with 119 control patients in sinus rhythm. Standard relative-delay phase reconstruction (40%-80% of cardiac cycle) was used, with additional absolute delay reconstruction performed when indicated. Image quality was scored both subjectively and objectively. RESULTS Patients with AF were older (68.5 +/- 14.0 years versus 62.5 +/- 12.1 years; P = 0.03). Maximum heart rate during injection was 102.5 +/- 30.4 beats/min and 70.8 +/- 16.6 beats/min in the AF and control groups, respectively (P < 0.01). Mean (+/-SD) Agatston score was 321 +/- 366 (range, 0-1158) and 361 +/- 743 (range, 0-3948) in the AF and control groups, respectively (P = 0.8). No difference was observed in the proportion of uninterpretable segments between the 2 groups, 7 (2%) in the AF group and 12 (1%) in the control group (P = NS). Two (8%) of 24 studies in the AF group and 12 (10%) of 119 studies in the control group were nondiagnostic (P = NS). Image quality was good or excellent in 13 (54%) of 21 AF cases compared with 94 (79%) of 119 control cases (P = 0.01). Absolute delay reconstruction was needed in 9 (38%) of 24 AF cases. CONCLUSIONS These preliminary data show that interpretable CCTA data can be obtained in patients with AF using DSCT. The need for absolute delay reconstruction is common.