Abstract 348: Low Radiation Dose, Prospectively ECG-Triggered Coronary CT Angiography: Can It Be Done in Patients With Cardiac Arrhythmia? Initial Experience
PURPOSE Prospective ECG-triggering (PT) can substantially lower patient radiation exposure at coronary CT angiography (cCTA) compared with retrospective ECG-gating. However, its use has mostly been restricted to patients with regular heart rhythms.
METHODS 12 patients with cardiac arrhythmia (excluding atrial fibrillation) underwent invasive catheter angiography (ICA) and cCTA using PT on a 128-slice CT scanner (Definition™ AS+, Siemens). Scan acquisition was performed with adaptive online modulation of the ECG triggering sequence, so that image acquisition occurs only during normo-rhythmic heart beats. Tube settings were adapted to patients’ body type (100–120kV with 200–300mAs). Beta-blockers were administered to patients with heart rates >70bpm. Two observers in consensus analyzed all cCTA studies for coronary artery stenosis using the AHA 15-segment model and findings were compared with ICA.
RESULTS Heart rate was 61±14bpm with a mean variation of 23±19bpm. Scan acquisition was completed using 4 or 5 acquisitions to cover the entire heart. DLP was 188±71mGy-cm resulting in a mean effective radiation dose equivalent of 2.6±1mSv. Without excluding any data, cCTA using PT had 97%/100% sensitivity, 93%/96% specificity, 85%/93% PPV, and 98%/100% NPV for diagnosing significant (>50%) stenosis on per-segment/per-patient analysis, respectively, compared with ICA.
CONCLUSION Our initial results suggest that, in patients with cardiac arrhythmia, cCTA using PT with adaptive online ECG monitoring enables non-invasive diagnosis of coronary artery stenosis with similar accuracy and comparably low radiation exposure as reported for normo-rhythmic populations.