Catheter ablation of the mitral isthmus eliminated ventricular tachycardia inducibility in 4 patients with a critical slow conduction zone, with 0 recurrences over 1 to 11 months.
Observational (n=12)
Does catheter ablation of the mitral isthmus prevent recurrence of ventricular tachycardia in patients with remote inferior infarction?
Catheter ablation targeting the mitral isthmus is an effective strategy for eliminating ventricular tachycardia in a subset of patients with prior inferior myocardial infarction.
BACKGROUND: Intraoperative mapping studies suggest that an isthmus of myocardium between the mitral valve annulus and the border of inferior myocardial infarction may play a role in the genesis of ventricular tachycardia. We examined the frequency with which a slow conduction zone within the mitral isthmus was critical to the maintenance of ventricular tachycardia associated with remote inferior infarction in patients undergoing catheter ablation. METHODS AND RESULTS: In 4 of 12 patients, a critical zone of slow conduction was identified within the mitral isthmus. In each of these patients, two characteristic and morphologically distinct tachycardias were induced: a left bundle (rS in V1, R in V6), left superior axis morphology and a right bundle (R in V1, QS in V6), right superior axis morphology (cycle length, 610 to 320 ms). In each patient, a zone of slow conduction, shared by both morphologies, was characterized by diastolic potentials with electrogram-QRS intervals of 85 to 161 ms (21% to 47% of tachycardia cycle length) and entrainment with concealed fusion during pacing associated with stimulus-QRS intervals of 81 to 400 ms (20% to 91% of tachycardia cycle length). In each patient, a single radiofrequency energy application at the shared site of slow conduction eliminated inducibility of both morphologies. During follow-up of 1 to 11 months, no patient had recurrent tachycardia. CONCLUSIONS: The mitral isthmus contains a critical region of slow conduction in some patients with ventricular tachycardia after inferior myocardial infarction, providing a vulnerable and anatomically localized target for catheter ablation. Characteristic tachycardia morphologies may provide clinical markers for this underlying mechanism.
Wilber et al. (1995) conducted an observational in Ventricular tachycardia associated with inferior infarction (n=12). Catheter ablation was evaluated on Elimination of tachycardia inducibility and recurrence. Catheter ablation of the mitral isthmus eliminated ventricular tachycardia inducibility in 4 patients with a critical slow conduction zone, with 0 recurrences over 1 to 11 months.