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Ablation Lesion Characterization in Scarred Substrate Assessed Using Cardiac Magnetic Resonance.

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.

SUBMITTER: Tao S

PROVIDER: S-EPMC6355250 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Ablation Lesion Characterization in Scarred Substrate Assessed Using Cardiac Magnetic Resonance.

Tao Susumu S Guttman Michael A MA Fink Sarah S Elahi Hassan H Patil Kaustubha D KD Ashikaga Hiroshi H Kolandaivelu Aravindan D AD Berger Ronald D RD Halushka Marc K MK Schmidt Ehud J EJ Herzka Daniel A DA Halperin Henry R HR

JACC. Clinical electrophysiology 20181226 1

<h4>Objectives</h4>This study examined radiofrequency catheter ablation (RFCA) lesions within and around scar by cardiac magnetic resonance (CMR) imaging and histology.<h4>Background</h4>Substrate modification by RFCA is the cornerstone therapy for ventricular arrhythmias. RFCA in scarred myocardium, however, is not well understood.<h4>Methods</h4>We performed electroanatomic mapping and RFCA in the left ventricles of 8 swine with myocardial infarction. Non-contrast-enhanced T<sub>1</sub>-weight ...[more]

PMID: 30678791

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Project description:BackgroundThe impact of ablation parameters on acute tissue lesion formation after pulmonary vein isolation (PVI) has not been sufficiently evaluated in patients with atrial fibrillation. Radiofrequency ablation lesion can be visualized by late gadolinium enhancement cardiac magnetic resonance (LGE-CMR). We sought to quantitatively analyze the relationship between ablation parameter and tissue lesion following PVI at different segments of pulmonary vein (PV) using LGE-CMR.MethodsTwenty-one patients with atrial fibrillation who underwent PVI procedure were retrospectively enrolled. All patients underwent LGE-CMR examination within 3 days after radiofrequency ablation. Ablation parameters during PVI were documented, including lesion size index (LSI), force-time integral (FTI), power, contact force, temperature, and time of duration. The ablation point was projected onto 3-dimensional (3D) left atrial shell constructed base on LGE-CMR and corresponding image intensity ratio (IIR) was calculated on the same shell. A tissue lesion point was defined when the LGE-CMR IIR was > 1.2.ResultsIn total, 1,759 ablation points were analyzed. The ablation parameters and IIRs for each PV segment were significantly different (P < 0.0001). IIRs corresponding to ablation points at posterior of PV tended to be higher than those at non-posterior of PV when similar ablation parameters were applied during ablation. LSI was a better predictor of tissue lesion existence following PVI than FTI, contact force, power, temperature, and duration time at non-posterior wall of PV. The IIR showed positive correlation with LSI at non-posterior wall of PV (non-posterior of right PV, r = 0.13, P = 0.001, non-posterior of left PV, r = 0.26, P < 0.0001).ConclusionWhen similar ablation parameters were applied during PVI, the posterior wall of PV had more severe tissue lesion than non-posterior wall of PV. Therefore, it was reasonable to decrease ablation energy at posterior wall of PV. Moreover, LSI was a better index to reflect tissue lesion quality following PVI at non-posterior of PV.

Project description:BackgroundIn patients with angina and nonobstructive coronary artery disease (NOCAD), confirming symptoms due to coronary microvascular dysfunction (CMD) remains challenging. Cardiac magnetic resonance (CMR) assesses myocardial perfusion with high spatial resolution and is widely used for diagnosing obstructive coronary artery disease (CAD).ObjectivesThe goal of this study was to validate CMR for diagnosing microvascular angina in patients with NOCAD, compared with patients with obstructive CAD and correlated to the index of microcirculatory resistance (IMR) during invasive coronary angiography.MethodsFifty patients with angina (65 ± 9 years of age) and 20 age-matched healthy control subjects underwent adenosine stress CMR (1.5- and 3-T) to assess left ventricular function, inducible ischemia (myocardial perfusion reserve index [MPRI]; myocardial blood flow [MBF]), and infarction (late gadolinium enhancement). During subsequent angiography within 7 days, 28 patients had obstructive CAD (fractional flow reserve [FFR] ≤0.8) and 22 patients had NOCAD (FFR >0.8) who underwent 3-vessel IMR measurements.ResultsIn patients with NOCAD, myocardium with IMR <25 U had normal MPRI (1.9 ± 0.4 vs. controls 2.0 ± 0.3; p = 0.49); myocardium with IMR ≥25 U had significantly impaired MPRI, similar to ischemic myocardium downstream of obstructive CAD (1.2 ± 0.3 vs. 1.2 ± 0.4; p = 0.61). An MPRI of 1.4 accurately detected impaired perfusion related to CMD (IMR ≥25 U; FFR >0.8) (area under the curve: 0.90; specificity: 95%; sensitivity: 89%; p < 0.001). Impaired MPRI in patients with NOCAD was driven by impaired augmentation of MBF during stress, with normal resting MBF. Myocardium with FFR >0.8 and normal IMR (<25 U) still had blunted stress MBF, suggesting mild CMD, which was distinguishable from control subjects by using a stress MBF threshold of 2.3 ml/min/g with 100% positive predictive value.ConclusionsIn angina patients with NOCAD, CMR can objectively and noninvasively assess microvascular angina. A CMR-based combined diagnostic pathway for both epicardial and microvascular CAD deserves further clinical validation.

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Ablation Lesion Characterization in Scarred Substrate Assessed Using Cardiac Magnetic Resonance.

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Ablation Lesion Characterization in Scarred Substrate Assessed Using Cardiac Magnetic Resonance.

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