Optimal heart rate threshold for phase selection in beta-blocker-free coronary CT angiography using second-generation...

Beta-blocker-free coronary CT angiography (CCTA) improves workflow, but is often limited by motion artifacts at higher heart rates (HRs). Advances such as faster gantry rotation and second-generation motion correction (SSF2) may overcome these limitations. We aimed to determine the optimal HR cutoff for phase selection using SSF2.

We retrospectively analyzed 368 patients who underwent CCTA without beta-blockers using a 256-row CT scanner (rotation time, 0.234 ​s). Systolic and diastolic phases were acquired over two consecutive heartbeats, with images reconstructed with and without SSF2. Image quality was graded on a 5-point Likert scale across seven coronary segments: proximal and distal portions of the three main coronary arteries and the left main trunk. Exams were deemed evaluable when all segments scored ≥3, allowing one distal segment to score 2. Receiver operating characteristic (ROC) curve analysis identified the optimal HR cutoff. Diagnostic performance for ≥50% stenosis was assessed in patients undergoing invasive coronary angiography (ICA).

Among 279 patients (median HR, 64 bpm), SSF2 significantly improved image quality and evaluability in both phases (all P ​< ​0.001). The optimal HR cutoff was 67 bpm, yielding 91.8% evaluability. At HR ​≤ ​67 bpm, diastolic SSF2+ images were superior (P ​≤ ​0.01); at HR ​> ​67 bpm, systolic SSF2+ images were optimal (P ​< ​0.001). In 50 patients with ICA, HR-guided phase selection achieved sensitivity, specificity, and accuracy of 91.3%, 88.3%, and 89.0%, respectively.

SSF2 enabled reliable beta-blocker-free CCTA. An HR cutoff of 67 bpm effectively guided phase selection, achieving 91.8% evaluability.