IJBEM, Vol. 5, No. 1, 2003

Linear Ablation During Sinus Rhythm for
Life-Threatening Ventricular Tachycardia in
Patients with Ischemic Cardiomyopathy Using Carto System

A.M. Wnuk-Wojnar, C. Czerwinski, A. Hoffmann, S. Nowak, E. Konarska-Kuszewska,
D. Urbanczyk, J. Krauze, and M. Trusz-Gluza.

1^st Department of Cardiology, Silesian Medical Academy, Katowice, Poland

Abstract. Ventricular tachycardias in patients with low ejection fraction after myocardial infarction can be life-threatening in spite of ICD implantation because these VTs are often incessant or very frequent (electrical storm). In addition, induced VTs are often unstable, preventing extensive mapping to localize all VT circuits. A total of 30 patients (24 males and 6 females) after myocardial infarction with ejection fraction < 30%, 2-6 months after ICD implantation were referred for RF ablation because of: recurrent VT in 22 patients, an incessant VT in 5 patients and unmappable, polymorphic VT/VF in 3 patients. Electro-anatomic mapping (EAM) was performed using CARTO system in all but 5 patients (incessant VTs) during sinus rhythm. Voltage maps were used to determine the area of dense scar (<0.5 mV), normal myocardium (>1.5 mV) and border zone (>0.5 mV and <1.5 mV). Two levels of voltage were selected to define the scar: 0.1 mV and 0.5 mV. The conducting isthmus (CI) defined by the presence of a channel of consecutive electrograms with a voltage amplitude higher than the voltage recorded in 2 surrounding scar areas was identified in 17 patients. Extensive sets of linear ablations were done around areas of scar (3-6 lines per patient) and across CI. In patients with incessant VTs the arrhythmia was terminated during RF application. In 3 patients ablation session was repeated because of VT reccurrencs after 6-7 months and in 1 patient after 2 years. No complications were observed after ablation. Mean fluoroscopy time was 7.2 + 3.4 min. No worsening in ejection fraction was observed during follow-up (ECHO). During 3-20 months of follow-up 11 patients are free of arrhythmia (ICD Holter). One patient died from refractory heart failure. In 9 patients 1-2 VF episodes were DC terminated, in further 8 patients single, asymptomatic, ATP terminated VTs were recorded. In 1 patient after 4 unsuccessful ablation sessions HTx was done. In conclusion, the voltage definition of the scar is helpful for CI identification, and EAM during sinus rhythm is safe and effective method to determine target sites for RF lines applications even in patients with severely depressed LV function, unstable and unmappable ventricular tachycardia.