Preprocedural magnetic resonance imaging for image-guided catheter ablation of scar-related ventricular tachycardia

Abstract

To present and validate a highly automated MRI analysis workflow for image-guided catheter ablation of scar-related ventricular tachycardia (VT) ablation procedures. A cohort of 15 post-infarction patients underwent MRI prior to VT ablation. The MRI study included a black-blood turbo spin echo sequence for visualizing the aortic root and ostium of the left main (LM) coronary artery, and a 3D late gadolinium enhanced sequence for visualizing the LV anatomy and myocardial scar substrate. Semi-automated segmentation of the LV, aortic root and ostium of LM was performed, followed by fully automated segmentation of myocardial scar. All segmented structures were aligned using an automated image registration algorithm to remove inter-scan displacement. MRI was integrated at the beginning of the procedure after mapping a single LM point. The integration performance was compared to that of the traditional iterative closest point (ICP) method. The proposed method required a single LM mapping point only, compared to 255 ± 43 points with the ICP method. The single-point method achieved a mean point-to-surface distance of 4.9 ± 1.5 mm on the LV surface and 5.1 ± 1.7 mm on the aorta surface (ICP: 3.7 ± 0.8 and 9.2 ± 7.2 mm, P < 0.05). The Cohen's kappa coefficient between the MRI-defined and EAM-defined scar was 0.36 ± 0.16 for the presented method, significantly higher than that of ICP method (0.23 ± 0.21, P = 0.03), indicating more accurate scar substrate localization during integration. This study demonstrated the feasibility of preprocedural MRI integration into the VT ablation procedure, with highly automated image analysis workflow and minimal mapping effort.

Ventricular Tachycardia (VT) Substrate Characteristics: Insights from Multimodality Structural and Functional Imaging of the VT Substrate Using Cardiac MRI Scar, 123I-Metaiodobenzylguanidine SPECT Innervation, and Bipolar Voltage

“…However, histologically, fibrosis patterns ranged from homogeneous to patchy and to diffuse, with decreasing accuracy of detection by CMR. Prior studies of ischemic VT in which CMR scar was compared with EAM showed a good but imperfect correlation, with a significant mismatch in up to 1 of 3 patients (3), and a rather modest correlation with Cohen k coefficients (ranging from 0.36 (23) to 0.7 (24)). Indeed, studies with CMR and EAM showed consistently high scar transmurality points with nearly preserved voltage (1,3,10,19), supporting the notion that bipolar amplitude and CMR-determined interstitial fibrosis are closely related but represent 2 nonidentical aspects of pathophysiologic scar remodeling.…”

Multi-Modality Imaging for the Identification of Arrhythmogenic Substrates Prior to Electrophysiology Studies

“…Similarly, noninvasive cardiac imaging has been also evolving, playing now a relevant role in the characterization of patients with VAs. For example, in patients with nonischemic cardiomyopathy (NICM), multimodality imaging can help in identifying the arrhythmogenic substrate and in characterizing the specific anatomical–functional components of the ventricular tachycardia (VT) circuits ( 2 , 3 , 6 – 9 ).…”

Multimodality Imaging to Guide Ventricular Tachycardia Ablation in Patients with Non-ischaemic Cardiomyopathy

“…In these patients, multimodality imaging can help to identify arrhythmogenic substrate and critical components of VT circuits, leading to decreased radiofrequency ablation time, total procedure time, and improved acute and long-term ablation success rates. [ 11 – 17 ] In contrast, the impact of pre-procedural imaging to guide VT ablation in NICM differs based on the underlying NICM aetiology. Pre-procedural imaging can visualise the presence of epicardial substrates and predict when epicardial mapping may be warranted.…”