Abstract 17172: Pre Ablation Voltage Mapping Can Alter VT Inducibility

Introduction: VT inducibility is often used to assess the efficacy of VT ablation. Sinus rhythm voltage maps (VMs) are used to guide ablation of VT substrate, but catheter manipulation may mechanically traumatize critical sites, altering VT inducibility. We prospectively evaluated the effect of VM on VT inducibility. Methods: Twenty-nine patients (mean age 62, 70% ischemic cardiomyopathy) with planned VT ablation underwent initial programmed electric stimulation (PES). Fifteen patients then underwent VM followed by repeat PES and 14 patients underwent a waiting period with ICE imaging and transseptal puncture but no VM (imaging group) before repeat PES. Responses to repeat PES were categorized as type I if the same VT was induced, type II if a different VT was induced, and type III if no VT was inducible. Results: In the VM group, the same VT was inducible in 3 patients, a different VT in 9, and no VT in 3 patients (figure). In contrast, those in the imaging group had the same VT induced in 10 patients, a different VT in 3 and no VT in 1 patient. There was no difference in the number of extrastimuli needed to induce VT between the two PES in either group. VT cycle length in the VM group was shorter after mapping (295 vs 331ms), although this was not statistically significant. There was no difference between the groups in anesthesia method, time between initial and second PES, type of cardiomyopathy, or ejection fraction. Conclusions: The mechanical effects of VM can alter inducibility of VT independent of ablation. This may contribute to late recurrences of VT by preventing mapping of clinically relevant VT circuits, or falsely indicating effective ablation when PES is repeated only after ablation.