Ablation Lesion Characterization in Scarred Substrate Assessed Using Cardiac Magnetic Resonance

Susumu Tao, Michael A. Guttman, Sarah Fink, Hassan Elahi, Kaustubha D. Patil, Hiroshi Ashikaga, Aravindan Kolandaivelu, Ronald D Berger, Marc K Halushka, Ehud Schmidt, Daniel Herzka, Henry R Halperin

Research output: Contribution to journalArticle

Abstract

Objectives: This study examined radiofrequency catheter ablation (RFCA) lesions within and around scar by cardiac magnetic resonance (CMR) imaging and histology. Background: Substrate modification by RFCA is the cornerstone therapy for ventricular arrhythmias. RFCA in scarred myocardium, however, is not well understood. Methods: We performed electroanatomic mapping and RFCA in the left ventricles of 8 swine with myocardial infarction. Non-contrast-enhanced T1-weighted (T1w) and contrast-enhanced CMR after RFCA were compared with gross pathology and histology. Results: Of 59 lesions, 17 were in normal myocardium (voltage >1.5 mV), 21 in border zone (0.5 to 1.5 mV), and 21 in scar (<0.5 mV). All RFCA lesions were enhanced in T1w CMR, whereas scar was hypointense, allowing discrimination among normal myocardium, scar, and RFCA lesions. With contrast-enhancement, lesions and scar were similarly enhanced and not distinguishable. Lesion width and depth in T1w CMR correlated with necrosis in pathology (both; r2 = 0.94, p < 0.001). CMR lesion volume was significantly different in normal myocardium, border zone, and scar (median: 397 [interquartile range (IQR): 301 to 474] mm3, 121 [IQR: 87 to 201] mm3, 66 [IQR: 33 to 123] mm3, respectively). RFCA force-time integral, impedance, and voltage changes did not correlate with lesion volume in border zone or scar. Histology showed that ablation necrosis extended into fibrotic tissue in 26 lesions and beyond in 14 lesions. In 7 lesions, necrosis expansion was blocked and redirected by fat. Conclusions: T1w CMR can selectively enhance necrotic tissue in and around scar and may allow determination of the completeness of ablation intra- and post-procedure. Lesion formation in scar is affected by tissue characteristics, with fibrosis and fat acting as thermal insulators.

Original languageEnglish (US)
Pages (from-to)91-100
Number of pages10
JournalJACC: Clinical Electrophysiology
Volume5
Issue number1
DOIs
Publication statusPublished - Jan 1 2019

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Keywords

  • cardiac magnetic resonance
  • myocardial infarction
  • non-contrast-enhanced T-weighted imaging
  • radiofrequency catheter ablation
  • ventricular arrhythmia

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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