Mapping and radiofrequency catheter ablation of the three types of sustained monomorphic ventricular tachycardia in nonischemic heart disease

Introduction. Sustained monomorphic ventricular tachycardia (VT) associated with nonischemic cardiomyopathy (CMP) is uncommon. Optimal approaches to c atheter mapping and ablation are not well characterized, but they are likel y to depend on the VT mechanism. The purpose of this study was to evaluate the mechanisms of sustained monomorphic VT encountered in nonischemic CMP a nd to assess the feasibility, safety, and efficacy of catheter radiofrequen cy ablation for treatment. Methods and Results: Twenty-six consecutive patients with nonischemic CMP r eferred for management of recurrent VT were studied. In 16 (62%) patients, VT was related to a region of abnormal electrograms consistent with scar an d the response to pacing suggested a reentrant mechanism. In 5 (19%) patien ts, VT was due to bundle branch or interfascicular reentry, In 7 (27%) pati ents, the VT mechanism was focal automaticity, 4 of whom had evidence of ta chycardia-induced CMP, After catheter ablation targeting parts of reentrant circuits, VT was not inducible in 8 (53%) of 15 patients with scar-related reentry, was modified in 5 (33%) patients, and still was inducible in 2 (1 3%) patients. Ablation was successful in 5 of 5 patients with bundle branch reentry and in 6 of 7 patients with a focal automaticity mechanism. Overal l, catheter ablation abolished clinical recurrence of VT in 20 (77%) of 26 patients during a follow-up of 15 +/- 12 months. Conclusion: Three different mechanisms of VT are encountered in patients wi th nonischemic CMP, The mapping and ablation approach varies with the type of VT. In this selected population, the overall efficacy was 77%.