Summary
LGE imaging of left atrial scar is promising and can detect pre/post ablation procedures however further quality control required to accurately depict lesion distribution
Background
We tested the hypothesis that cardiovascular magnetic resonance (CMR) imaging can reliably distinguish the presence or absence of ablation lesions by blinded analysis of pre and post ablation imaging.
Methods
Consecutive patients with paroxysmal AF in a randomised study comparing pulmonary vein isolation by wide area circumferential radiofrequency ablation (WACA) to ostial ablation with a cryo-balloon (CRYO) underwent CMR late gadolinium enhancement (LGE) imaging pre- and 3 months post ablation. Imaging was anonymized for blinded analysis of (1) LGE images, and (2) a 3D fusion image with LGE projected onto a segmented LA surface (thresholding set at 5 SD above mean ventricular signal). Scans were categorised using both assessment techniques separately as pre or post ablation, and if post ablation, whether lesions were in an ostial or WACA distribution.
Results
LGE imaging was performed in 50 patients (aged 61 ± 10 years, 72% male). Sensitivity and specificity for detection of ablation lesions was 60% and 96% on LGE imaging, or 88% and 82% respectively on 3D fusion imaging. Detection of WACA and CRYO lesion sets were correct in 14/24 and 16/26 respectively on LGE imaging, or 21/24 and 23/26 on 3D fusion imaging. Assessment of lesion distribution was correct for 13/50 from LGE images (4/24 for WACA and 9/26 for CRYO) and 26/50 from 3D fusion images (p = 0.013; 13/24 for WACA and 13/26 for CRYO).
Conclusions
LGE imaging of atrial scar after ablation therapy is feasible. The technique still needs quality control standards established in order to determine the appropriate SD setting and to judge whether lack of peri-ostial scar is due to a sub-optimal scan or myocardial recovery
Funding
National Institute of Health Research (UK).
Table 1.
Diagnostic accuracy of detecting atrial scarring in blinded analysis of pre and post ablation MR images.
| Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | |
|---|---|---|---|---|
| Late Gadolinium Enhancement | 60 | 96 | 94 | 68 |
| Segmented Fusion images | 88 | 82 | 81 | 87 |
Table 2.
Accuracy of MR images to locate atrial scarring according to ablation technique
| Correct identification of lesion distribution | LGE | Fusion segmented image |
|---|---|---|
| WACA | 4/24 (17%) | 13/24 (54%) |
| Cryo | 9/26 (35%) | 13/26 (50%) |