A study undertaken in the UK has shown that radiofrequency ablation of scar-related ventricular tachycardia, using robotic navigation, is safe and feasible and has resulted in 95% reduction in total implantable cardioverter defibrillator (ICD) therapy burden at six months. Moreover, when compared to manual guided ablation, acute and long-term outcomes with robotic navigation are similar.
“Ventricular tachycardia ablation is used to reduce and prevent recurrence of ICD therapy; however, in long-term follow-ups recurrence rates with this therapy remain high,” said Vishal Luther (Department of Cardiac Electrophysiology, Hammersmith and St Mary’s Hospital, Imperial College Healthcare NHS trust, London, UK) investigator and presenter of the study at the Heart Rhythm Congress (4–7 October, Birmingham, UK).
“Using analogue in-vivo studies at equivalent ablation settings, we have demonstrated more rapid and greater voltage amplitude reduction using robotic guided ventricular tachycardia ablation compared to a manual approach. In addition, macroscopically transmurality was achieved robotically and it was not achieved manually [the inability to achieve effective transmurality might explain the reason why there is ventricular tachycardia recurrence],” explained Luther.
Due to the lack of data looking at the effectiveness of robotic catheter ablation of ventricular tachycardia, Luther noted, the aim of this study was to assess the feasibility and safety of robotically guided scar-related ventricular tachycardia ablation (with the Sensei Robotic System/Hansen Medical) and retrospectively compare acute and long-term outcome data to a cohort of patients who underwent manual ablation.
Endpoints were twofold: firstly the researchers looked acutely at the post procedural programmed ventricular tachycardia stimulation effect and grouped patients to three outcomes: ventricular tachycardia that was no inducible, non-clinical ventricular tachycardia as inducible and clinical ventricular tachycardia inducible. Secondly, they looked at the burden of ICD therapy (ATP and shocks) in the long term. Patients with post infarct ventricular tachycardia and those with recurrent appropriate ICDs were included.
Luther highlighted that patients in the robotic arm had a restriction to their power settings as 30W (irrigated catheter) at 60 seconds based on previous studies, which showed an increased risk of complication at 45 degrees. In the manual group, there was not restriction to the power settings.
A total of 60 patients who underwent scar related ventricular tachycardia ablation from the Imperial College EP Database (January 2010 – January 2014) were analysed. Of those, 26 patients met the inclusion criteria. Twelve patients underwent ablation with robotic navigation and 14 had manual ablation. Luther noted that two of the patients in the manual group were followed-up externally so this study includes data based on 12 patients in the manual group. Baseline characteristics and comorbidities were similar in both groups.
Luther told delegates that regarding procedural characteristics, there was a greater number of patients who required urgent procedure in the robotic arm (75%) as opposed to the manual group (33%) and this was statistically significant (p=0.01). In addition, there was a higher number (33%) of previous failed ventricular tachycardia ablations in the robotic group compared to the manual group (8%); however, this was not statistically significant, Luther noted.
Comparing intra-procedural data, there was a higher number of induced ventricular tachycardia (2.4±1.9) in the robotic cohort compared to the manual cohort (1.7±1.0). “This suggests that patients in the robotic arm may have had a more complex arrhythmic substrate,” Luther said.
As there was a restriction in the ablation delivery, there was a significantly lower time of ablation lesion in the robotic group (59.4±3.4) compared to the manual group (71.9±19.1). Fluoroscopy times were also higher in the robotic group (42.6±11.4) compared to the manual group (32.7±18.6). The duration of the procedure was higher in the robotic group (312±91min) compared to the manual arm (218±93min), but none of these results were statistically different, Luther commented.
In terms of acute ablation outcome data, the results were comparable (ventricular tachycardia non-inducible: p=0.68, non-clinical: p=0.67, ventricular tachycardia inducible: p=1).
There were no intraprocedural complications on each group. Percentage of patients needing redo procedures were similar (robotic: 21%, manual: 29%) and mortality events were also similar (robotic: 33%, manual: 33%).
In terms of pre- and post-procedural ICD therapy burden at six months, the robotic group in particular, had an “impressive reduction from 32 events to 2.5 events, which is translated in 95% reduction in ICD therapy burden,” noted Luther. The manual group also showed a 74% reduction in ICD therapy burden. Comparing ICD therapy burden post-ablation, there was no difference in outcome between robotic and manual ablation.
In conclusion, Luther told delegates, radiofrequency ablation of scar-related ventricular tachycardia using the Sensei Robotic System is both safe and feasible including patients presenting urgently with multiple ICD therapies and storm and for patients who have failed manual ablation. Also, when compared to a series of patients who underwent manual guided ablation, acute and long-term outcomes were similar.