MRI Accurately Visualizes RF Ablation Delivery Targeted to MRI-Defined Arrhythmia Substrates in the Left Ventricle

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.