Incidence and relevance of nonreentrant monomorphic ventricular tachycardia in patients with frequent implantable cardioverter defibrillator interventions.

BACKGROUND: Nonreentrant ventricular tachycardia (VT) originates in hearts without structural disease but occasionally can occur in patients with different cardiomyopathies equipped with an implantable cardioverter defibrillator (ICD).
METHODS: In a series of 142 ICD recipients with structural heart disease undergoing ablation for recurrent or incessant monomorphic VT, nonreentrant VTs were identified.
RESULTS: Nonreentrant VTs were the cause of appropriate ICD interventions in 12 patients (8.4%). The underlying heart disease was nonischemic cardiomyopathy in eight patients, prior myocardial infarction in two patients, and valvular cardiomyopathy in two patients with a mean left ventricular ejection fraction of 42 ± 7%. Unresponsiveness to antitachycardia pacing and repetitive spontaneous re-initiation of the VT after defibrillation was the cause of frequent ineffective ICD interventions including repetitive ICD shocks in these patients. Using ICD interrogation, one or more episodes of a severe electrical storm (≥3 serial efficacious ICD shocks within 15 min) were more frequently documented in patients with nonreentrant VTs (10/12) than in patients with scar-related reentrant VTs (36/115). The origin of the nonreentrant VT was the left ventricular outflow tract in seven patients, the right ventricular outflow tract in three patients, and the tricuspid and mitral annulus in each one patient. Catheter ablation including epicardial mapping in 2 patients eliminated the nonreentrant VT in 11 of 12 patients and prevented recurrent VT storm.
CONCLUSIONS: Repetitive nonreentrant VTs may be ineffectively treated by ICD interventions and can be the cause of an electrical storm in different cardiomyopathies.