Image quality and radiation dose of single heartbeat 640-slice coronary CT angiography: a comparison between patients with chronic atrial fibrillation and subjects in normal sinus rhythm by propensity analysis.

Objectives: To evaluate image quality and radiation dose of single heartbeat 640-slice coronary CT angiography (CCTA) in patients with chronic Atrial Fibrillation (cAF) in comparison with subjects in normal sinus rhythm.

Methods: A cohort of 71 patients with cAF was matched with 71 subjects in normal sinus rhythm (NSR) and HR≤65 bpm using a matched by propensity analysis. All subjects underwent a single heartbeat CCTA with prospective gating. In subjects with cAF, we manually established the acquisition of data only from a single heartbeat. Mean effective dose and image quality, with both objective and subjective measures, were assessed.

Results: 96.4% of all segments in the cAF group had diagnostic image quality. The rate of subjects with at least one non-diagnostic segment was 14% and 2.8% (p=0.031) in the cAF and NRS groups, respectively. In the cAF group, the percentage of patients with at least one non-diagnostic segment for acquisition HR≤72 was 1.8% (1/55), and it did not significantly differ from the NSR group (2.8%; 2/71) (p=1.0). Objective quality parameters did not show a statistically significant difference between the two groups. The mean effective dose was 4.24±1.24 mSv in the cAF group and 2.67±0.5 mSv in the sinus rhythm group (p<0.0001) with an increase by 59% in the cAF group with respect to the SNR group.

Conclusions: A single heartbeat acquisition protocol with a 640-slice prospectively ECG-triggered CT angiography may be feasible in patients with cAF and HR below 72 bpm at the CT acquisition, although mean effective dose of this protocol in cAF group was 59% higher than in sinus rhythm one. In patients with cAF and a heart rate higher than 72 bpm, CCTA tends to have more movement-associated artefacts.