Background:
Electrical storm (ES) is a life-threatening condition, and catheter ablation can be curative in this syndrome. Rhythmia Mapping System (RMS, Boston Scientific) is a novel system that allows for ultra-fast, high density 3D mapping. The aim of this study was to assess feasibility, safety and short-term effectiveness of catheter ablations performed with the use of RMS for ES.

Material and methods:
Ablations for ES in five patients who underwent first mapping with the use of RMS system at our centre (2016) were compared with the procedures in a cohort of 56 consecutive patients mapped for ES with the Carto system (Biosense Webster) between 2010 and 2015.

Results:
Time to construct RMS maps equaled 41min and the average map had 8776 points (214 points per minute). Procedure (160min), fluoroscopy duration (23min) and radiologic exposure (333mGy) were significantly (all p<0.05) greater in RMS procedures, they were however similar (all p=NS) to procedural parameters during first 5 Carto procedures in 2010. Arrhythmia mapping was possible in 80% of RMS patients, and in 27% Carto procedures (p=0.01). Acute success (100 vs 91%), complication-rates (0 vs 7%) and short-term recurrence-rates within 2 months follow-up (20 vs. 32%, all p=NS) were similar in RMS and Carto-mapped subjects.

Conclusions:
Mapping and ablation of ES with the RMS are comparably safe, feasible and effective like Carto procedures. Longer procedure duration and higher fluoroscopy burden associated with RMS are typical for early stages of the learning curve. RMS may be more effective in mapping during arrhythmia.