Electrical storm and heart failure worsening in implantable cardiac defibrillator patients

AIMS: In patients with an implantable cardiac defibrillator (ICD), electrical storm (ES) is associated with increased sudden and non-sudden cardiac mortality, the latter largely due to worsening heart failure (HF). Aim of this study is to test the association between ES and impending pump failure in patients with known chronic HF and ICD. METHODS AND RESULTS: Inclusion criteria were a previous history of chronic HF, former ICD implant, and hospital admission for HF worsening, or ES, or unclustered ventricular tachyarrhythmias (VTs/VFs). Patients with concomitant stable HF or HF worsening due to another specific cause were excluded. Primary endpoint was all cause mortality. Main secondary endpoint was time to first rehospitalization. Prospective, observational study on 146 patients: 34 with ES, 30 with unclustered VTs/VFs, and 82 with HF worsening. During the 5 years of follow-up, there was no significant difference between survival estimates between ES and HF worsening (P = 0.7), while both were significantly lower than survival of unclustered VT/VF patients (all log rank P < 0.05). Hospitalization-free time was significantly lower in both the ES group and in the HF worsening group when compared with unclustered VT/VF patients (all log rank P < 0.05). There was no significant difference between hospitalization estimates between ES and HF worsening. CONCLUSION: Heart failure patients admitted for ES have major similarities with patients admitted for HF clinical decompensation such as similar survival, cause of death and time to first rehospitalization. There is evidence suggesting that, in this population, ES could be considered as a clinical manifestation of HF worsening.