Clusters of ventricular tachycardias signify impaired survival in patients with idiopathic dilated cardiomyopathy and implantable cardioverter defibrillators

OBJECTIVES This retrospective study was undertaken to provide data on occurrence, significance and therapy of ventricular tachyarrhythmia (VT) clusters (VTCs) in patients with dilated cardiomyopathy (DCM) and implantable cardioverter defibrillators (ICDs). BACKGROUND Data on the clinical significance of VTCs are lacking in patients with DCM and ICDs. METHODS Baseline characteristics of 106 consecutive patients with DCM and ICDs were prospectively collected, and chart reviews and episode data retrospectively analyzed. A VTC was defined as ≥3 sustained VTs/24 h. RESULTS During a mean follow-up of 33 ± 23 months, 73 patients (68.9%) had recurrent VT or ventricular fibrillation (VF), 43 patients (40.6%) suffered only single VTs and 30 patients (28.3%) experienced 52 clusters of VTs. Actuarial survival free of VT or VF was 44.6%, 33.0% and 26.5%, and survival free of VTC was 77.3%, 72.2% and 67.1% after one, two and three years, respectively. Independent predictors of VT clusters were heart failure before ICD implantation (p = 0.033), presenting monomorphic VT (p = 0.044), EF <0.40 (p = 0.014) and inducible mVT, especially with right bundle branch block and superior axis configuration (p < 0.001). Survival free of recurrent VTCs was 50.8%, 38.1% and 19.0% after one, two and three years, respectively. Once a VTC had occurred, only 56.7%, 46.4%, 30.9% and 15.5% of patients survived and were not transplanted after one, two, three and four years, respectively. Survival was even more reduced if a VTC was associated with cardiac decompensation: 65.6% and 21.9% after one and two years, respectively. CONCLUSIONS Despite antiarrhythmic intervention, clusters of VTs occur and recur frequently in patients with DCM. They signify impaired survival, especially if they are associated with cardiac decompensation, and may be a harbinger of progressive myocardial deterioration rather than a primarily arrhythmic problem. The benefit of ICD therapy may therefore be low in these patients.