Catheter ablation of ventricular tachycardia with intracardiac shocks: results in 33 patients.

Catheter electrical ablation of ventricular tachycardia (VT) was attempted in 33 patients who had recurrent unimorphic VT refractory to 3.7 +/- 1.2 (mean +/- SD) antiarrhythmic drugs. Their mean age was 56 +/- 14 years. Twenty-two patients had coronary artery disease, six had other types of heart disease, and five had no structural heart disease. The mean left ventricular ejection fraction was 0.34 +/- 0.17. Thirty patients had only one documented morphologic type of spontaneous VT, whereas three patients had more than one. One to four shocks of 100 to 300 J each were delivered to the endocardial exit site of VT, as identified by endocardial activation mapping and pace-mapping. In each patient endocardial activation at the exit site of VT preceded the onset of the QRS complex (mean activation time -50 +/- 30 msec). Pace-mapping was possible in 26 patients, and in all but two patients the QRS complexes during VT and during pacing at the exit site of VT were very similar in at least 10 of 12 electrocardiogr...