Assessment of radiofrequency ablation lesions by CMR imaging after ablation of idiopathic ventricular arrhythmias.
OBJECTIVE
To identify and characterize ablation lesions after radiofrequency (RF) catheter ablation of ventricular arrhythmias in patients without prior myocardial infarction and to correlate the ablation lesions with the amount of RF energy delivered and the clinical outcome.


BACKGROUND
Visualization of RF energy lesions after ablation of ventricular arrhythmias might help to identify reasons for ablation failure.


METHODS
In a consecutive series of 35 patients (19 women, age: 48 +/- 15 years, ejection fraction: 0.56 +/- 0.12) without structural heart disease who were referred for ablation of ventricular arrhythmias, cardiac magnetic resonance imaging with delayed enhancement was performed before and after ablation. Ablation lesions were sought in the post-ablation cardiac magnetic resonance images. 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 RF energy delivered.


RESULTS
In 25 of 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 cm(3), with a mean endocardial area of 3.5 +/- 3.0 cm(2). The largest lesions (mean volume of 2.9 +/- 2.1 cm(3) with an endocardial area of 6.4 +/- 3.4 cm(2)) 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 versus nonirrigated ablation catheters (1.0 +/- 0.73 vs. 2.0 +/- 2.1 cm(3), p = 0.09). Identification of ablation lesions in patients with a failed procedure identified the sites where ineffective RF energy lesions were created.


CONCLUSIONS
RF ablation lesions can be detected long term after an ablation procedure targeting ventricular arrhythmias in patients without previous infarction. Lesion size correlates with the amount of RF energy delivered and is largest when a targeted arrhythmia originates in a papillary muscle.
Ilg
Karl
K
Department of Internal Medicine, University of Michigan Health System, Ann Arbor, Michigan, USA.
Baman
Timir S
TS
Gupta
Sanjaya K
SK
Swanson
Scott
S
Good
Eric
E
Chugh
Aman
A
Jongnarangsin
Krit
K
Pelosi
Frank
F
Crawford
Thomas
T
Oral
Hakan
H
Morady
Fred
F
Bogun
Frank
F
D000328:Adult; D017115:Catheter Ablation / Q000295:instrumentation; D003287:Contrast Media; D022062:Electrophysiologic Techniques, Cardiac; D004867:Equipment Design; D005260:Female; D019786:Gadolinium DTPA; D006352:Heart Ventricles / Q000473:pathology / Q000601:surgery; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000601:surgery*; D013997:Time Factors; D016896:Treatment Outcome; D018879:Ventricular Premature Complexes / Q000175:diagnosis* / Q000601:surgery*
D003287:Contrast Media; D019786:Gadolinium DTPA