Ablation Lesion Characterization in Scarred Substrate Assessed Using Cardiac Magnetic Resonance
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Author + information
- Susumu Tao, MD, PhDa,∗ (stao5.1978{at}gmail.com),
- Michael A. Guttman, MSa,
- Sarah Fink, MSa,
- Hassan Elahi, MSb,
- Kaustubha D. Patil, MDa,
- Hiroshi Ashikaga, MD, PhDa,b,
- Aravindan D. Kolandaivelu, MDa,
- Ronald D. Berger, MD, PhDa,
- Marc K. Halushka, MD, PhDc,
- Ehud J. Schmidt, PhDa,
- Daniel A. Herzka, PhDb and
- Henry R. Halperin, MD, MAa,b,d
- aDivision of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
- bDepartment of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, Maryland
- cDepartment of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- dDepartment of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
- ↵∗Address for correspondence:
Dr. Susumu Tao, Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Carnegie 568, Baltimore, Maryland 21287.
Graphical abstract
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.
- cardiac magnetic resonance
- myocardial infarction
- non-contrast-enhanced T1-weighted imaging
- radiofrequency catheter ablation
- ventricular arrhythmia
Footnotes
Supported by a Heart Rhythm Society Fellowship in Cardiac Pacing and Electrophysiology 2017 to 2018 (Dr. Tao) and National Heart, Lung, and Blood Institute grants R01HL094610 (Dr. Halperin) and R21-EB023515 (Dr. Herzka). Dr. Kolandaivelu has received research support from Abbott. Dr. Schmidt has received research support from Abbott. Dr. Halperin has received royalties from Imricor. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
All authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Clinical Electrophysiology author instructions page.
- Received April 17, 2018.
- Revision received October 30, 2018.
- Accepted November 1, 2018.
- 2019 American College of Cardiology Foundation
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