CT coronary angiography in atrial fibrillation: a comparison of radiation dose and diagnostic confidence with retrospective gatingvsprospective gating with systolic acquisition

Benjamin Clayton; Carl Roobottom; Gareth Morgan‐Hughes

doi:10.1259/bjr.20150533

September 4, 2015British Journal of RadiologyOpen Access

CT coronary angiography in atrial fibrillation: a comparison of radiation dose and diagnostic confidence with retrospective gatingvsprospective gating with systolic acquisition

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Why the study?

Does prospective ECG gating with systolic acquisition reduce radiation dose and improve diagnostic confidence compared to retrospective gating in patients with atrial fibrillation undergoing CT coronary angiography?

Structured PICO

Does prospective ECG gating with systolic acquisition reduce radiation dose and improve diagnostic confidence compared to retrospective gating in patients with atrial fibrillation undergoing CT coronary angiography?

P

Population

50 patients with atrial fibrillation undergoing CT coronary angiography (25 consecutive patients per group)

I

Intervention

Prospective ECG gating with systolic acquisition for CT coronary angiography

C

Comparator

Unmodulated, retrospective electrocardiographic (ECG) gating for CT coronary angiography

O

Outcome

Radiation dose and diagnostic confidence (rated using a 5-point Likert scale by blinded expert readers)surrogate

Prospective ECG gating with systolic acquisition for CT coronary angiography in patients with atrial fibrillation significantly reduces radiation exposure and improves diagnostic confidence compared to retrospective gating.

Implication

May support prospective gating to cut dose and boost confidence in AF CTCA; leaves open confirmation by randomized trials.

Abstract

OBJECTIVE: To compare unmodulated, retrospective electrocardiographic (ECG) gating to prospective ECG gating with systolic acquisition for CT coronary angiography (CTCA) in patients with atrial fibrillation (AF), considering the radiation dose and the diagnostic confidence achieved with each technique. METHODS: A retrospective service evaluation was conducted before and after prospective gating with systolic acquisition replaced retrospectively gated imaging for patients with AF undergoing CTCA at our institution. 25 consecutive patients were examined in each group. The scan parameters and radiation dose information had been collected in a prospective fashion. The image sets were read by blinded, expert readers who rated their diagnostic confidence using a 5-point Likert scale. RESULTS: The radiation dose received by patients was significantly greater in the retrospectively gated group than those being scanned using prospective gating (21 vs 5.9 mSv, p < 0.01). The prospective gating technique was also associated with greater diagnostic confidence (mean, per-patient score 3.09 vs 3.78, p = 0.02). CONCLUSION: Prospective gating with systolic acquisition appears to improve diagnostic confidence at a significantly reduced radiation dose compared with retrospective gating in patients with AF. ADVANCES IN KNOWLEDGE: The use of prospective gating with systolic triggering significantly reduces the radiation exposure to patients in AF undergoing CTCA. The same protocol also appears to improve diagnostic confidence.