Electro anatomically guided catheter ablation of ventricular tachycardias causing multiple defibrillator shocks

With conventional techniques, RF catheter ablation is difficult in patients with unstable VT or with multiple VTs. The feasibility of RF catheter abla tion guided by three-dimensional electroanatomic mapping technique in patie nts whose implanted ICD continued to deliver multiple shocks due to VT desp ite use of antiarrhythmic medications was assessed in 19 patients (15 men, 4 women; mean age [+/- SD] 70 +/- 7 years). All had a prior history of MI a nd subsequently had received an ICD due to VT. During the 12-week preablati on period, these patients received 31 +/- 15 shocks (range 4-62 shocks) due to refractory monomorphic VTs. An electroanatomic mapping technique using the CARTO system was performed to delineate scar tissue. RF catheter ablati on was then performed at appropriate sites identified by pacemapping and by substrate mapping. Seventeen patients were on amiodarone at the time of ab lation. Twenty-seven VTs were documented clinically, and 45 were induced du ring electrophysiological evaluation. Of the 45 tachycardias induced, 38 VT s were targeted for ablation. Catheter ablation was performed during sinus rhythm in 31 episodes and during VT in 7 episodes. During a mean follow-up of 26 +/- 8 weeks (range 18-48 weeks), 13 (66%) patients had no recurrence of VT (P < 0.0001) and antiarrhythmic drugs were discontinued or the number of medications reduced in 17 patients (P < 0.0001). Electroanatomic mappin g is helpful in identifying sites for catheter ablation in highly symptomat ic patients with refractory VT associated with myocardial scarring.