Guidance of Intra-Operative Ventricular Tachycardia Ablation during LVAD Implantation with Pre-operative Cardiac MRI

Abstract

Introduction Ventricular tachycardia (VT) is common in ischemic cardiomyopathy (ICM). Ablation maybe required to reduce ICD shocks and improve the quality of life. Preoperative VT mapping is an invasive electrophysiologic study prior to the surgery which heart failure patients may not tolerate. Substrate modification is usually done in an open epicardial approach during LVAD implantation. Non-invasive mapping techniques have not been described before. In this case pre-operative cardiac magnetic resonance (CMR) imaging was used to plan VT scar mapping and guide intra-operative cryoablation that was done while performing LVAD implantation. Case Report 69-year-old man with ICM (ejection fraction of 23%) and biventricular cardioverter-defibrillator (ICD). He has history of VT, four ablations, and on mexiletine and amiodarone. He had VT-related syncope terminated with anti-tachycardia pacing (ATP). ICD interrogation showed 15 appropriate shocks and >100 ATP therapies since the device implantation 6 months prior. In hospital he had slow monomorphic VT (slow cycle length 650 msec) with left bundle-branch morphology and superior axis positive in AVR. Milrinone was started for cardiogenic shock (cardiac index of 1.81 L/min/m2). He was not a transplant candidate so he was scheduled for destination therapy LVAD. Before the procedure he had sustained monomorphic VTs refractory to ATP requiring ICD shock. Cardiac MRI showed large chronic infarct with marked remodeling and transmural delayed enhancement in the inferoseptal, inferior, and inferolateral segments at the base a mid-ventricular portions of the left ventricle (LV) extending into the inferior aspect of the apical LV. Six myocardial segments equivalent was involved with transmural infarct. We decided to do an intra-operative VT ablation during LVAD implantation. Intraoperatively the LVAD ring was anchored to the apex with sutures. LV incision was made, and cryoablation of the inferoseptal towards inferolateral wall was performed using Cryo3 cryoICE catheter. Corresponding to the scar on MRI ablation lesions were created and the lesions were overlapping (from 3 to 9 o'clock position). The incision site was also cryoablated with a total of ten cryoablations. Conclusion This is the first case to use cardiac MRI for preoperative VT mapping and did correspond to the lesions seen intra-operatively. This is a novel non-invasive mapping tool for heart failure patients undergoing surgical cryoablation . At 1 month follow up the patient has had 68 episodes of non-sustained VT, and 8 episodes of VT, successfully treated with ATP.