Prospective vs retrospective ecg gated protocol: how to overcome chronic atrial fibrillation as contraindication to mdct-ca

Purpose: Chronic atrial fibrillation (CAF) represents a relative contraindication to MDCT-CA. Aim of the study is to evaluate diagnostic accuracy, image quality and the optimal reconstruction phase to image the coronary tree. Methods and Materials: Among 509 patients, 16 consecutive cases of CAF were selected. 64 slice MDCT equipment was used with retrospective or prospective ECG-gated dose saving protocols, depending on HR and BMI. Optimal reconstruction window was recorded. Conventional Coronary Angiography (CCA) was considered as the standard of reference. Results: 12/16 (75%) patients were studied with retrospective ECG gated protocol, 4/16 (25%) were studied with prospective triggering Step & Shoot. Mean BMI resulted to be 25.37 (range 19.5-31.7). Mean HR was 68.6 bpm (range 46-105 bpm). 12/16 (75%) were evaluated in end-diastolic phase (4/16 with prospective gating) with HR ranging from 46 to 105 bpm, 3/16 (19%) in mid-end sistolic phase with HR ranging from 66 to 100 bpm, 1/16 (6%) in both, end-diastolic and mid-end sistolic phase (HR 84 bpm). Image quality was good in 11/16 (69%) cases, discrete in 3/16 (19%) of the cases. Conclusion: Optimal image quality can be better achieved by using retrospective ECG gated protocol in order to always obtain the adequate reconstruction interval, independently from the presence of CAF.