Substrate-modification using electroanatomical mapping in sinus rhythm to treat ventricular tachycardia in patients with ischemic cardiomyopathy

Summary The treatment especially of frequent ischemic VT remains a challenge for medical and catheter ablation procedures. We evaluated the efficacy of a substrate-based procedure to eliminate clinical VTs in this patient collective.Methods In 25 consecutive patients (ejection fraction 37±12%) with frequent symptomatic medically refractory ischemic VT (with recurrent ICD-shocks), left ventricular anatomic scar mapping (Biosense Webster CARTO™) was performed in order to modify the underlying myocardial substrate. Scar tissue was identified as having bipolar voltages <0.5 mV. Prior to the procedure an electrophysiological study (EPS) to determine number and morphology of inducible VTs was performed. Linear ablation procedures (8 mm tip, 70 Watts, 70 °C) were based on the findings of scar areas and proximity to anatomic obstacles. Correct location of ablation was documented by similarity of the morphology during pace-mapping. Follow-up included clinical evaluation, ICD holter interrogation plus holter ECG recording.Results The clinical VT was eliminated by linear catheter ablation in 23/25 patients (92%) (failure due to unstable catheter position during transaortic approach in 1 and epicardial origin of VT in 1). In 16/23 patients (70%) complete success could be produced with no VT inducible after substrate modification (1.7±1.0 lines per patient). In 7 patients (30%) only partial success was documented with further VTs inducible after ablation. No procedure-related complications occurred. During follow- up (10±4 months) 4 patients (16%) had occurrences of new VTs documented on ICD holter (3 patients with initially partial success and 1 with initial complete success) differing in cycle length and morphology from the clinical VT. Comparing patients with complete to those with partial success, there was a statistically significant difference of 93 vs. 48% freedom of arrhythmia (p=0.03). No difference in regard to baseline characteristics existed in these two patient subgroups.Conclusions Ablation of frequent VTs in patients with ischemic cardiomyopathy can be safely performed using electro-anatomic scar mapping with a high procedural success of 90%. Based on the morphological findings, linear ablation can suppress inducibility of all VTs in 70% of patients with high mid-term efficacy. In patients with only partial ablation success, non-clinical VTs often occur early during follow-up (50%).