Background: Ventricular Tachycardia (VT) mapping strategies for scar-dependent monomorphic VT have traditionally involved entrainment and pace mapping. The increasing importance of substrate mapping has emerged with several methods described to target the VT site of origin and diastolic conduction channels (CCs), such as, low amplitude ventricular activity (LAVA) potential and decrementing evoked potential (DEEP) mapping. Furthermore, recent state-of-the-art multipolar mapping catheters have been developed to enhance mapping capabilities.
Objective: The purpose of this study was to investigate whether VT ablation long-term outcome was improved with the use of high-density mapping catheters combining complementary mapping strategies into a strict mapping and ablation workflow.
Methods: Structural heart VT ablation patients underwent a strict procedural workflow combining substrate, entrainment, pace mapping and contemporary activation mapping methodologies. Substrate mapping included the identification of CCs with ripple mapping, voltage scanning and DEEP potential mapping. Mapping catheters compared included the HD Grid, Pentaray, Livewire Duodeca and point-by-point RF catheters. Primary endpoints were recurrent ATP, appropriate shock, asymptomatic non-sustained VT (NSVT) or all-cause death and the primary analysis compared long term outcomes in the HD Grid mapping group to all other mapping catheters.
Results: A total of 73 structural heart VT ablation procedures were performed with 33 HD Grid mapping cases and 40 non-HD Grid cases with no significant difference in baseline characteristics. Substrate mapping was performed in 97% (71/73) of cases and activation maps used to guide ablation were successfully generated in 82% of HD Grid cases, 64% of Pentaray cases, 92% Duodeca cases and 33% of RF mapping cases (p=0.025) with a similar trend observed with entrainment and pace mapping (HD Grid 58%; Pentaray 45%, Duodeca 83%, RF 17%; p=0.039). A greater number of VTs were mapped with multipolar catheters and thereafter ablated. Complete elimination of clinical and non-clinical VTs which was achieved in 79% of HD Grid cases, 55% of Pentaray cases, 83% Duodeca and 33% of RF mapping cases (p=0.04). Survival curve analysis showed a significantly higher end-point free survival for both ATP and appropriate shock in the HD Grid group compared to other mapping catheters. With a mean follow-up of 372 ± 234 days, 97% and 100% of HD Grid patients were free of recurrent ATP and shock, respectively, compared to 64% and 82% in the Pentaray group; 58% and 83% in the Duodeca group; 33% and 33% in the RF mapping group.
Conclusions: A wide variety of mapping catheters can be used with an armamentarium of strategies to define VT ablation targets. We have shown a step-wise improvement in survival free from ICD therapies as the density of mapping capability increases. By using high density mapping catheters and combining complementary mapping strategies in a strict procedural workflow, long-term clinical outcomes are improved.
