Multimodal Assessment for Ventricular Tachycardia Substrate

The process of target determination is shown in Figure 1. In Step 1 (Figure 1, Left panel), an electrophysiologist estimated the VT substrate or lesion site. We followed the method used by the Washington University team.⁸ (link) The areas with findings obtained from electrophysiological, structural, and functional information were virtual points plotted on a 17-segment model. Currently, the weighting of the 3 types of scores for each segment is not defined: the findings were converted to 1 point each, and the points calculated for each area were used as the total score.
Figure 1.

Study protocol. After registration with the Japan Registry for Clinical Trials, target and radiation planning comprised 3 steps. As part of Step 1, electrical, structural, and functional data were combined. Step 2 involved estimation of VT substrates and foci, as well as risk assessment of surrounding organs. Planning is repeated with targeting and contouring. Step 3 involves repeated calculation and determination of the optimal target volume, with permanent follow-up after radiotherapy. ECG, electrocardiogram; EPS, electrophysiological study; EVM, electroanatomic voltage mapping; ¹⁸F-FDG-PET, 18F-fluorodeoxyglucose positron emission tomography; HR, high resolution; ¹²³IMIBG, 123I-metaiodobenzylguanidine; MRI, magnetic resonance imaging; NSVT, non-sustained ventricular tachycardia; OAR, organ at risk; PVC, premature ventricular contraction; ^{99 m}Tc-TF, 99 m-technetium tetrofosmin; TCT, thoracic computer tomography; UCG, ultrasound cardiography; VT, ventricular tachycardia.

Electrophysiological assessment for predicting the origin of VT using 12-lead ECG during VT or non-sustained VT (NSVT) was based on the algorithm published by Andreu et al.⁹ (link) EPS is useful for detecting VT-supporting channels considered potential substrates of scar-related VT, which were referenced by induced VT morphology, cut-off adjustment of the voltage map, and pace mapping during sinus rhythm.¹⁰ (link)
Structural substrate information was acquired from ultrasound cardiography (UCG), CT, MRI, and electroanatomic voltage mapping (EVM). Myocardial foci were noted on the basis of myocardial wall thinning, calcification, and areas of gadolinium-delayed contrast.
Single-photon emission CT (SPECT) and positron emission CT (PET) were used to obtain functional substrate information. Scintigraphy included 99 m-technetium tetrofosmin (^{99 m}Tc-TF), ¹²³I-metaiodobenzylguanidine (MIBG), and ¹²³I-β-methyl-p-iodophenyl pentadecanoic acid (BMIPP).¹¹ (link) Arrhythmic substrates were assessed by calculating the area of poor perfusion and denervation, perfusion/innervation mismatch,¹² (link)^,¹³ (link) decreased heart-to-mediastinum (H/M) ratio,¹⁴ (link) and increased regional washout in the myocardium.¹⁵ (link)

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Amino M., Kabuki S., Kunieda E., Hashimoto J., Sugawara A., Sakai T., Sakama S., Ayabe K., Ohno Y., Yagishita A., Kobayashi Y., Ikari Y, & Yoshioka K. (2023). Interim Report of a Japanese Phase II Trial for Cardiac Stereotactic Body Radiotherapy in Refractory Ventricular Tachycardia　― Focus on Target Determination ―. Circulation Reports, 5(3), 69-79.

Publication 2023

12 lead ecg 123i 18f fluorodeoxyglucose 99 technetium Bmipp Calcification Ct pet Denervation Electrical Electrocardiogram Electrophysiological study Gadolinium Heart Mediastinum Metaiodobenzylguanidine Myocardium Pentadecanoic acid Perfusion Positron emission tomography Premature ventricular contraction Radiotherapy Risk assessment Scar Scintigraphy Sinus Tomography Ultrasound Ventricular tachycardia

Corresponding Organization :

Other organizations : Tokai University, National Institutes for Quantum and Radiological Science and Technology, Tokai University Hachioji Hospital

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Variable analysis

independent variables

Electrophysiological assessment for predicting the origin of VT using 12-lead ECG during VT or non-sustained VT (NSVT)
Structural substrate information acquired from ultrasound cardiography (UCG), CT, MRI, and electroanatomic voltage mapping (EVM)
Functional substrate information obtained from SPECT and PET (99m-technetium tetrofosmin (99mTc-TF), 123I-metaiodobenzylguanidine (MIBG), and 123I-β-methyl-p-iodophenyl pentadecanoic acid (BMIPP))

dependent variables

Identifying the VT substrate or lesion site
Estimating VT substrates and foci
Assessing risk of surrounding organs

control variables

The weighting of the 3 types of scores (electrical, structural, and functional) for each segment is not defined, and the findings were converted to 1 point each

positive controls

The method used by the Washington University team for estimating the VT substrate or lesion site
The algorithm published by Andreu et al. for electrophysiological assessment to predict the origin of VT using 12-lead ECG during VT or non-sustained VT (NSVT)

negative controls

Not mentioned

Annotations

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