Successful treatment of idiopathic left ventricular outflow tract tachycardia by catheter ablation or minimally invasive surgical cryoablation

Idiopathic right ventricular outflow tract tachycardia is readily amenable to radiofrequency catheter ablation. However, treatment modalities for left ventricular outflow tract tachycardia are not well defined. Out of 37 pati ents with idiopathic outflow tract tachycardia referred for catheter ablati on, in 3 patients tachycardia originated from the left ventricular outflow tract. On the surface EGG, all left ventricular tachycardias exhibited an i nferior axis with a predominant negative QRS complex in lead I. Heart rate during tachycardia ranged from 115 to 170 beats/min. During electrophysiolo gical testing, 1 patient had inducible tachycardia on orciprenaline challen ge, 1 patient had inducible tachycardia at baseline, and 1 patient had ince ssant tachycardia. In two patients, earliest ventricular activation was rec orded from the endocardial left ventricular outflow tract at an anterolater al and an anterior site, respectively. A distinct high frequency spike prec eeded the QRS onset by 66/78 ms. Application of radiofrequency energy succe ssfully eliminated tachycardia at these sites. In one patient, tachycardia originated from the epicardial left ventricular outflow tract. Mapping of t he anterior interventricular vein revealed a fractionated low amplitude sig nal occurring 46 ms before QRS onset. After failure of catheter ablation fr om the corresponding endocardial site, successful minimally invasive surgic al focal cryoablation of the epicardial target region was performed. During a follow-up period ranging from 7 to 12 months, all patients remained free of tachycardia. In conclusion, ventricular tachycardia arising from the le ft ventricular outflow tract may require endo- and epicardial mapping. Succ essful treatment is achieved by radiofrequency catheter ablation or minimal ly invasive surgical cryoablation.