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Lesion Size and Lesion Maturation After Radiofrequency Catheter Ablation for Ventricular Tachycardia in Humans With Nonischemic Cardiomyopathy

2021; Lippincott Williams & Wilkins; Volume: 14; Issue: 8 Linguagem: Inglês

10.1161/circep.121.009808

1941-3149

Claire A. Glashan, William G. Stevenson, Katja Zeppenfeld,

Cardiac pacing and defibrillation studies

HomeCirculation: Arrhythmia and ElectrophysiologyVol. 14, No. 8Lesion Size and Lesion Maturation After Radiofrequency Catheter Ablation for Ventricular Tachycardia in Humans With Nonischemic Cardiomyopathy Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessLetterPDF/EPUBLesion Size and Lesion Maturation After Radiofrequency Catheter Ablation for Ventricular Tachycardia in Humans With Nonischemic Cardiomyopathy Claire A. Glashan, MD William Stevenson, MD, PhD Katja ZeppenfeldMD, PhD Claire A. GlashanClaire A. Glashan Willem Einthoven Center for Cardiac Arrhythmia Research and Management, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands (C.A.G., K.Z.). Search for more papers by this author , William StevensonWilliam Stevenson https://orcid.org/0000-0002-2118-7893 Department of Cardiology, Vanderbilt University Medical Center, Nashville, TN (W.S.). Search for more papers by this author , and Katja ZeppenfeldKatja Zeppenfeld Correspondence to: Katja Zeppenfeld, MD, PhD, Leiden University Medical Center, Department of Cardiology, Cardiology (C5-P), P.O. Box 9600, Leiden, 2300 RC, the Netherlands. Email E-mail Address: [email protected] https://orcid.org/0000-0002-7034-1017 Willem Einthoven Center for Cardiac Arrhythmia Research and Management, Department of Cardiology, Leiden University Medical Center, Leiden, the Netherlands (C.A.G., K.Z.). Search for more papers by this author Originally published16 Aug 2021https://doi.org/10.1161/CIRCEP.121.009808Circulation: Arrhythmia and Electrophysiology. 2021;14:e009808Human data on the evolution of radiofrequency catheter ablation (RFCA) lesions are limited and largely lacking in nonischemic cardiomyopathy (NICM). Morphological changes after RFCA in postinfarction swine models have been well described and show significantly smaller lesions in scar compared with nonscar areas.1 Importantly, patterns of fibrosis in NICM are different from postmyocardial infarction scars2 and may influence lesion size. The importance of understanding radiofrequency lesion evolution is also highlighted by a recent study of histology after stereotactic radioablation (SBRT) in which prior radiofrequency ablation likely complicates interpretation of the effects of SBRT.3The data that support the findings of this study are available from the corresponding author upon request. All patients were treated according to our standard clinical protocol and provided informed consent for mapping and ablation. All patients or next of kin provided informed consent for postmortem analysis. Ten patients with NICM (male, median age 63 years [interquartile range (IQR), 56–66], 9/10 class IV/V variant) and ventricular tachycardia underwent electroanatomical mapping and irrigated-tip RFCA (45–50 W, 30 mL/min normal saline, maximum 43 °C, contact force >9g, duration 60 s) before death (transplantation in one). After death, the hearts were fixed, embedded in gelatin or HistOmer, and sectioned. Integration of EAM data with histology was performed as previously described.2 Ablation lesions were examined on gross pathology and histology (7-µm sections stained with Sirius red, hematoxylin cross-stained). In each patient, depth and width of the three largest isolated lesions were measured and the volumes calculated as ellipsoids.The median time between ablation and death was 39 days (range, 1–821). Ablation lesions were visible on pathology and histology within fibrotic areas. Median lesion width was 13.3 mm (IQR, 11.0–15.0), median depth 7.2 mm (IQR, 6.1–8.3), and volume 323.8 mm3 (IQR, 225.9–479.9). Median wall thickness was 14.3 mm (IQR, 11.2–15.9); thus, importantly, ablation lesions reached depths of 54.5% (IQR, 45.3–64.3) of the wall thickness.Recent (<30 days) ablation lesions were easily visible on gross pathology as semi-circular, endocardial lesions with hemorrhagic rims (Figure). Older lesions maintained the endocardial semi-circular shape but were fully scarred and white. On histology, the ablation lesions were also easily identified. Fresh lesions showed no fibrosis, rather denucleated, necrotic cells. Lymphocytic infiltration was seen around the lesion. Myocytes outside the rim were easily distinguished from necrotic tissue by the presence of nuclei. In patients with 21-, 28- and 49-day old lesions fibrosis had begun to form around the rim of the lesion. The interior of the lesion remained denucleated myocytes. The fibrotic rim appears to become thicker over time. Older lesions (≥343 days) were fully fibrotic without surrounding lymphocytic infiltration.We found that lesions after RFCA in NICM patients are of considerable size with lesion maturation over several weeks to months. In a recent study, lesion depths after irrigated RFCA with contact force sensing were studied in an swine model of reperfused myocardial infarction.1 The maximum achieved lesion depths (contact force 30g) were 5.1±0.6 mm, 3.3±0.7 mm, and 2.0±0.5 mm in normal myocardium, scar borderzone, and dense scar, respectively. The lesions created in our study population are considerably larger with a median depth of 7.2 mm. One possible explanation for the difference is different ablation settings used (45–50 W for 60 s versus 30 W for 30 s). However, the greater lesion depth may also be due to the difference in the nature of the scars.Radiofrequency energy heats the tissue adjacent to the catheter tip by resistive heating, followed by conductive heating to distant myocardium. It has been speculated that postinfarct scars are less prone to conductive heating compared to normal myocardium explaining the difference in lesion size.NICM scars, which are inhomogeneous and more diffuse,2 may allow for deeper penetration of radiofrequency energy compared to ischemic scars and thus account for the deeper lesions shown here.Given that the lesions reached depths of 54.5% of wall thickness, approaching the area of interest from 2 sides may allow for complete transmurality and elimination of deep substrates. However, in areas that cannot be reached from 2 sides (left ventricular summit, regions protected by fat), or areas with greater wall thickness (ie, hypertrophic cardiomyopathy), additional techniques are required. SBRT has been recently suggested if RFCA fails to eliminate the ventricular tachycardia substrate, which is more frequently encountered in patients with nonischemic scars. The course of tissue injury after SBRT is of great interest, but most patients who are treated have had radiofrequency ablation that failed. A recent paper described acute and chronic histological tissue changes following SBRT in humans. Their observations are consistent with our findings of radiofrequency lesions, highlighting the complexity of assessing ablation effects in this population.Here, we have clearly described the gross pathological and histological features of radiofrequency ablation lesions and described how they mature over time. We hope that this information provides future researchers with a benchmark to discriminate between naturally occurring scars, scar formed by radiofrequency ablation, and scars formed by other interventions (Figure).4Download figureDownload PowerPointFigure. Pathological and histological changes occuring in NICM tissue after radiofrequency (RF) ablation.Top, Basal short-axis slices. Number of days between RF ablation and explantation. Middle and bottom, Histological sections of ablation lesions, collagen-red, cytoplasm-yellow, nuclei-black. CF indicates contact force.Sources of FundingNone.Disclosures Dr Stevenson reports personal fees from Abbott, personal fees from Johnson and Johnson, personal fees from Boston Scientific, personal fees from Biotronik, and personal fees from Medtronic outside the submitted work; in addition, Dr Stevenson has a patent to Irrigated Needle ablation patent co-holder issued. The other authors report no conflicts.FootnotesFor Sources of Funding and Disclosures, see page 790.Correspondence to: Katja Zeppenfeld, MD, PhD, Leiden University Medical Center, Department of Cardiology, Cardiology (C5-P), P.O. Box 9600, Leiden, 2300 RC, the Netherlands. Email k.[email protected]nlReferences1. Tofig BJ, Lukac P, Nielsen JM, Hansen ESS, Tougaard RS, Jensen HK, Nielsen JC, Kristiansen SB. Radiofrequency ablation lesions in low-, intermediate-, and normal-voltage myocardium: an in vivo study in a porcine heart model.Europace. 2019; 21:1919–1927. doi: 10.1093/europace/euz247CrossrefMedlineGoogle Scholar2. Glashan CA, Androulakis AFA, Tao Q, Glashan RN, Wisse LJ, Ebert M, de Ruiter MC, van Meer BJ, Brouwer C, Dekkers OM, et al.. Whole human heart histology to validate electroanatomical voltage mapping in patients with non-ischaemic cardiomyopathy and ventricular tachycardia.Eur Heart J. 2018; 39:2867–2875. doi: 10.1093/eurheartj/ehy168CrossrefMedlineGoogle Scholar3. Robinson CG, Samson PP, Moore KMS, Hugo GD, Knutson N, Mutic S, Goddu SM, Lang A, Cooper DH, Faddis M, et al.. Phase I/II trial of electrophysiology-guided noninvasive cardiac radioablation for ventricular tachycardia.Circulation. 2019; 139:313–321. doi: 10.1161/CIRCULATIONAHA.118.038261LinkGoogle Scholar4. Kiani S, Kutob L, Schneider F, Higgins KA, Lloyd MS. Histopathologic and ultrastructural findings in human myocardium after stereotactic body radiation therapy for recalcitrant ventricular tachycardia.Circ Arrhythm Electrophysiol. 2020; 13:e008753. doi: 10.1161/CIRCEP.120.008753LinkGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetails August 2021Vol 14, Issue 8Article InformationMetrics Download: 216 © 2021 American Heart Association, Inc.https://doi.org/10.1161/CIRCEP.121.009808PMID: 34397261 Originally publishedAugust 16, 2021 Keywordstachycardiaradiationmyocardial infarctioncatheter ablationcardiomyopathyPDF download SubjectsArrhythmiasElectrophysiologyCatheter Ablation and Implantable Cardioverter-DefibrillatorCardiomyopathy