Abstract 2674: Assessment of Radiofrequency Ablation Lesions by Magnetic Resonance Imaging After Ablation of Idiopathic Ventricular Arrhythmias
Background: Visualization of radiofrequency energy lesions after ablation of ventricular arrhythmias might help to identify reasons for ablation failure. The purpose of this study was to identify and characterize ablation lesions after radiofrequency catheter ablation of ventricular arrhythmias in patients without prior myocardial infarction and to correlate the ablation lesions with the amount of radiofrequency (RF) energy delivered and the clinical outcome.
Methods: In a consecutive series of 35 patients (19 women, age: 48±15 years, EF 0.56±0.12) without structural heart disease who were referred for ablation of ventricular arrhythmias, cardiac magnetic resonance imaging (MRI) with delayed enhancement was performed before and after ablation. Ablation lesions were sought in the post-ablation MRIs. The endocardial area, depth and volume of the lesions were measured. Lesion size was correlated with the type of ablation catheter used and the duration of radiofrequency energy delivered.
Results: In 25/35 patients (71%), ablation lesions were identified by delayed enhancement a mean of 22±12 months after the initial ablation procedure. The mean lesion volume was 1.4±1.4 cm3, with a mean endocardial area of 3.5±3.0 cm2. The largest lesions (mean volume of 2.9±2.1 cm3 with an endocardial area of 6.4±3.4 cm2) were identified in patients in whom the arrhythmias originated in the papillary muscles. Ablation duration correlated with lesion size (R=0.67; p<0.001). There was no difference in lesion volume with irrigated vs non-irrigated ablation catheters (1.0±0.73 vs 2.0±2.1 cm3; p=0.09). Identification of ablation lesions in patients with a failed procedure identified the sites where ineffective RF energy lesions were created.
Conclusion: Radiofrequency ablation lesions can be detected long-term after an ablation procedure targeting ventricular arrhythmias in patients without prior infarction. Lesion size correlates with the amount of radiofrequency energy delivered and is largest when a targeted arrhythmia originates in a papillary muscle.