Background: We have previously developed the sense protocol functional substrate mapping technique for ventricular tachycardia (VT) ablation. However, functional substrate characterization can involve protracted mapping time.
Purpose: We incorporated the integration of magnetic resonance imaging (MRI) data using ADAS-3D software into the mapping workflow to integrate structural mapping information into the functional mapping substrate characterization in order to improve procedural efficiency.
Method: Cardiac MRIs were performed in 30 patients with ischaemic-related VT and VT therapy in the previous 6 months. These were processed with the ADAS-3D software to characterize the extent of ventricular scars and also ADAS corridors, which may correlate with VT channels. Focused substrate maps were then performed in patients, guided by the extent of ADAS scar and corridors, looking at the scar substrate in intrinsic rhythm and then functional channels using single extra pacing from the RV at 20 ms above ERP (SENSE2 Protocol). Specifically, healthy areas 2 cm beyond the scar border zone based on ADAS were not mapped in order to reduce substrate mapping time, and complete geometries were not created. Following delineation of functional channels, pace-mapping and entrainment mapping were used to confirm targets for ablation. The ADAS 3D MRI was integrated into the VT substrate map on Ensite-Precision with alignment to the aorta, RV and PA (Figure 1a,b). We compared our data with previous functional mapping data without the integration of MRI.
Results: Thirty patients (age 70 years; 20 male subjects) underwent ablation. Mean EF was 28%. The median procedure time was 161 minutes compared with 246 minutes (in our previous study p<0.001) (Figure 2a). The mean substrate mapping time was 32 min vs 63 min (p<0.001) (Figure 2b). The mean ablation time was 22 min vs 32 min (p=0.11). Overall, 85% of patients (17 of 20) were free from symptomatic VT/anti-tachycardia pacing or implantable cardioverter-defibrillator shocks at a median follow-up of 171 days. The mean VT burden was reduced from 22 events per patient in the 6 months pre-ablation to 1 event per patient in the median follow-up period of 171 days post-ablation (p=0.02). Mean shocks per-patient burden decreased from 3.5 to 0.08 in the same time period (p=0.03).
Conclusion: The SENSE2 protocol involves the integration of structural and functional data into the VT workflow for substrate characterization. It enables focused substrate maps to be performed without the need for complete geometry to be created in large ventricles. Outcomes compare favourably with our previous data but with significantly shorter procedure times. This streamlined workflow has the potential to improve care in VT ablation by shortening procedure times with similar outcomes, which may reduce risks for the patient. ❑
