Three-Dimensional Delayed-Enhanced Cardiac MRI Reconstructions to Guide Ventricular Tachycardia Ablations and Assess Ablation Lesions

Abstract

Voltage mapping is the primary tool for identifying sites for substrate-guided ventricular tachycardia (VT) ablation, but there are limitations in its application. Delayed-enhanced cardiac MRI (DE-CMRI) can facilitate VT ablations by providing complementary detail about myocardial scar location and geometry. We present the case of a patient with recurrent VT with left bundle branch block (LBBB)-right-side inferior axis morphology and a challenging voltage map. The patient was a 76-year-old man with a history of hypertension, type 2 diabetes mellitus, atrial fibrillation, and newly diagnosed dilated nonischemic cardiomyopathy (ejection fraction, 30%). He was transferred to our facility because of multiple episodes of monomorphic VT with a heart rate of 160 beats/min and an LBBB-right-side inferior axis morphology (Figure 1) consistent with an origin in the right ventricular outflow tract (RVOT). He required 2 episodes of electric cardioversion and amiodarone therapy, but the VT was refractory to amiodarone, so the patient underwent a VT ablation procedure. Figure 1. Clinical ventricular tachycardia with left bundle branch block-right-side inferior axis morphology. CMRI with a 1.5-T Siemens Avanto scanner was performed in multiple anatomic planes using T1-weighted and cine steady-state free precision sequences. Gadolinium-enhanced sequences to evaluate early myocardial perfusion and delayed myocardial enhancement were also performed, using 0.1 mL/kg gadobenate dimeglumine. DE-CMRI demonstrated midmyocardial scar in the anteroseptal region of the RVOT (Figure 2), which raised the possibility of a substrate-mediated VT. Figure 2. Preablation 2D delayed-enhanced cardiac MRI. Preablation short-axis views from base to apex, showing delayed gadolinium enhancement corresponding to midseptal scar in the anteroseptal area of the right ventricular outflow tract (arrows). Reformatted 2D slices using Amira software allowed the reconstruction of 3D models of the right ventricle (RV) and left ventricle (LV) anatomy with embedded myocardial scar. These were exported as 3D Carto-readable mesh files …