Magnetic Resonance Mapping of Catheter Ablation Lesions After Post-Infarction Ventricular Tachycardia Ablation

OBJECTIVES This study sought to describe cardiac magnetic resonance (CMR) characteristics of ablation lesions within post-infarction scar. BACKGROUND Chronic ablation lesions created during radiofrequency ablation of ventricular tachycardia (VT) in the setting of prior myocardial infarction have not been described in humans. METHODS Seventeen patients (15 men, ejection fraction 25 +/- 8%, 66 +/- 6 years of age) with CMR imaging prior to repeat ablation procedures for VT were studied. Electroanatomic maps from first-time procedures and subsequent CMR images were merged and retrospectively compared with electroanatomic maps from repeat procedures. RESULTS The delay between the index ablation procedure and the CMR study was 30 +/- 29 months. Late gadolinium-enhanced CMR revealed a confluent nonenhancing subendocardial dark core within the infarct-related scar tissue in all patients. Intracardiac thrombi were ruled out by transthoracic and intracardiac echocardiography. These core lesions matched the distribution of prior ablation lesions, and corresponded to unexcitable areas at repeat procedures. CONCLUSIONS Ablation lesions can be detected by CMR after VT ablation in post-infarction patients and have a different appearance than scar tissue. These lesions can be observed many months after an initial ablation. (C) 2021 by the American College of Cardiology Foundation.