Cardiac magnetic resonance and endocardial voltage mapping accurately defined atrial ablation injury, with optimal SI thresholds of 2.3 SD for acute LGE and 3.3 SD for chronic LGE.
Do specific signal intensity thresholds in CMR and endocardial voltage mapping accurately reflect acute and chronic atrial ablation injury compared to histopathology in a pig model?
This study identifies specific signal intensity thresholds for CMR that best match histological lesion volumes for acute and chronic atrial ablation injury, providing a foundation for better assessment of atrial substrate post-ablation.
AIMS: To provide a comprehensive histopathological validation of cardiac magnetic resonance (CMR) and endocardial voltage mapping of acute and chronic atrial ablation injury. METHODS AND RESULTS: 16 pigs underwent pre-ablation T2-weighted (T2W) and late gadolinium enhancement (LGE) CMR and high-density voltage mapping of the right atrium (RA) and both were repeated after intercaval linear radiofrequency ablation. Eight pigs were sacrificed following the procedure for pathological examination. A further eight pigs were recovered for 8 weeks, before chronic CMR, repeat RA voltage mapping and pathological examination. Signal intensity (SI) thresholds from 0 to 15 SD above a reference SI were used to segment the RA in CMR images and segmentations compared with real lesion volumes. The SI thresholds that best approximated histological volumes were 2.3 SD for LGE post-ablation, 14.5 SD for T2W post-ablation and 3.3 SD for LGE chronically. T2-weighted chronically always underestimated lesion volume. Acute histology showed transmural injury with coagulative necrosis. Chronic histology showed transmural fibrous scar. The mean voltage at the centre of the ablation line was 3.3 mV pre-ablation, 0.6 mV immediately post-ablation, and 0.3 mV chronically. CONCLUSION: This study presents the first histopathological validation of CMR and endocardial voltage mapping to define acute and chronic atrial ablation injury, including SI thresholds that best match histological lesion volumes. An understanding of these thresholds may allow a more informed assessment of the underlying atrial substrate immediately after ablation and before repeat catheter ablation for atrial arrhythmias.
Harrison et al. (Sun,) conducted a other in Atrial ablation injury (n=16). Cardiac magnetic resonance (T2W and LGE) and high-density voltage mapping vs. Histological examination was evaluated on Signal intensity (SI) thresholds that best approximated histological volumes. Cardiac magnetic resonance and endocardial voltage mapping accurately defined atrial ablation injury, with optimal SI thresholds of 2.3 SD for acute LGE and 3.3 SD for chronic LGE.