Refinement of CARTO-guided substrate modification in patients with ventricular tachycardia after myocardial infarction

Background Substrate modification guided by CARTO system has been introduced to facilitate linear ablation ofventricular tachycardia(VT)after myocardial infarction(MI).However,there is no commonly accepted standard approachavailable for drawing these ablation lines.Therefore,the aim of the present study was to practically refine this timeconsuming procedure.Methods Substrate modification was performed in 23 consecutive patients with frequent VTs after MI using the CARTOsystem.The initial target site(ITS)for ablation was identified by pace mapping(PM)during sinus rhythm and/orentrainment pacing(EM)during VT.According to the initial target site,two approaches were used.The initial target site inapproach one has a similar QRS morphology as VT and an interval from the stimulus to the onset of QRS cmplex(S-QRS)of50 ms during PM in sinus rhythm or a difference of the post pacing interval and VT cycle length30 msduring concealed entrainment pacing of VT;The initial target site in approach two has an similar QRS morphology as VTand an S-QRS of<50 ms during PM in sinus rhythm.Results Overall,50 lines were performed with a length of(35±11)mm.Procedure time averaged(232±56)minutes,fluoroscopy time(10±8)minutes.Sixteen patients were initially involved into approach one.After completion of 3±1ablation lines,no further VT was inducible in 13 patients.The remaining 3 patients were switched to use the alternativeapproach.However,in none of them the alternative approaches were successful.Approach two was initially used in 7patients.After completion of 3±1 ablation lines,no further VT was inducible in only 2 patients.The remaining 5 patientswere switched to approach one,which resulted in noninducibility of VT in 4 of them.The initial successful rate wassignificantly higher in the group of approach one compared to that in the group of approach two(13/16 patients vs 2/7patients,P=0.026).Conclusions The approach for substrate modification of VT after MI can be optimized by identifying the appropriateinitial target site with specific characteristics within the zone of slow conduction.The refined approach may facilitate linearablation of VT,and further reduce the procedure and fluoroscopy time.