MRI Accurately Visualizes RF Ablation Delivery Targeted to MRI-Defined Arrhythmia Substrates in the Left Ventricle
Objective:
Investigate the capacity of MRI to evaluate efficacy of radiofrequency (RF) ablations delivered to MRI-defined arrhythmogenic substrates.
Methods:
Baseline MRI was performed at 3 T including 3D LGE in a swine model of chronic myocardial infarct (N = 8). MRI-derived maps of scar and heterogeneous tissue channels (HTCs) were generated using ADAS 3D. Animals underwent electroanatomic mapping and ablation of the left ventricle in CARTO3, guided by MRI-derived scar maps. Post-ablation MRI (in vivo at 3 T in 5/8 animals; ex vivo at 1.5 T in 3/8) included 3D native T1-weighted IR-SPGR (TI = 700-800 ms) to visualize RF lesions. T1-derived RF lesions were compared against excised tissue. The locations of T1-derived RF lesions were compared against CARTO ablation tags, and segment-wise sensitivity and specificity of lesion detection were calculated within the AHA 17-segment model.
Results:
RF lesions were clearly visualized in HTCs, scar, and myocardium. Ablation patterns delivered in CARTO matched T1-derived RF lesion patterns with high sensitivity (88.9%) and specificity (94.7%), and were closely matched in registered MR-EP data sets, with a displacement of 5.4 ±3.8 mm (N = 152 ablation tags).
Conclusion:
Integrating MRI into ablative procedures for RF lesion assessment is feasible. Patterns of RF lesions created using a standard 3D EAM system are accurately reflected by MRI visualization in healthy myocardium, scar, and HTCs comprising the MRI-defined arrhythmia substrate.
Significance:
MRI visualization of RF lesions can provide near-immediate ( 24 h) assessment of ablation, potentially indicating whether critical MRI-defined ventricular tachycardia substrates have been adequately ablated.
Insights
Magnetic resonance imaging (MRI) can effectively assess radiofrequency (RF) ablation efficacy. MRI visualization accurately reflects RF lesion patterns in cardiac tissue, aiding in evaluating ablation success for arrhythmia substrates.
Area of Science:
- Cardiovascular Imaging
- Medical Device Technology
- Electrophysiology
Background:
- Radiofrequency (RF) ablation is a key treatment for cardiac arrhythmias.
- Assessing the efficacy of RF lesions in real-time, especially within complex substrates, remains a challenge.
- Magnetic resonance imaging (MRI) offers high-resolution anatomical visualization.
Purpose of the Study:
- To investigate the capability of MRI to evaluate the effectiveness of RF ablations.
- To determine if MRI can assess ablations targeting MRI-defined arrhythmogenic substrates.
- To correlate MRI-based lesion assessment with electroanatomic mapping data.
Main Methods:
- A swine model with chronic myocardial infarction was used (N=8).
- Baseline 3 Tesla (3T) MRI with 3D Late Gadolinium Enhancement (LGE) identified scar and heterogeneous tissue channels (HTCs).
- Animals underwent CARTO3 electroanatomic mapping and left ventricle ablation guided by MRI scar maps. Post-ablation MRI visualized RF lesions using T1-weighted imaging, compared against excised tissue and CARTO ablation tags.
Main Results:
- RF lesions were clearly visualized by MRI in HTCs, scar, and myocardium.
- MRI-detected ablation patterns closely matched CARTO3 delivery patterns with high sensitivity (88.9%) and specificity (94.7%).
- Registered MR-EP data showed minimal displacement (5.4 ±3.8 mm) between MRI lesions and ablation tags.
Conclusions:
- Integrating MRI for RF lesion assessment during ablative procedures is feasible.
- MRI visualization accurately reflects RF lesion patterns in various cardiac tissue types, including healthy myocardium, scar, and HTCs.
- MRI provides a near-immediate assessment of ablation efficacy for critical ventricular tachycardia substrates.
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