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Published on: February 28, 2012
Relation between total shock energy and mortality in patients with implantable cardioverter-defibrillator
Taro Tenma1, Hisashi Yokoshiki1, Hirofumi Mitsuyama2
1Department of Cardiovascular Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Japan.
Insights
Increased Implantable Cardioverter-Defibrillator (ICD) shock energy is linked to higher mortality. This association is particularly notable in patients with low left ventricular ejection fraction or atrial fibrillation.
Area of Science:
- Cardiology
- Medical Devices
- Clinical Research
Background:
- Implantable Cardioverter-Defibrillators (ICDs) are crucial for preventing sudden cardiac death.
- Previous studies linked ICD shocks to mortality, but the impact of total shock energy remained unexplored.
Purpose of the Study:
- To investigate the association between total shock energy delivered by ICDs and patient mortality.
- To identify patient subgroups at higher risk for mortality related to ICD shock energy.
Main Methods:
- Retrospective analysis of data from 316 patients who received an initial ICD implantation.
- Collection of ICD shock energy data over a 3-year period post-implantation.
- Statistical analysis to determine the relationship between shock energy and mortality, adjusting for confounding factors.
Main Results:
- A significant association was found between higher total shock energy and increased all-cause mortality (adjusted HR 1.26 per 100 joules).
- Patients with high shock energy accumulation (≥182 joules) had lower survival rates compared to those with low accumulation or no shock.
- The link between high shock energy and mortality was more pronounced in patients with low left ventricular ejection fraction (LVEF ≤40%) or atrial fibrillation (AF).
Conclusions:
- Elevated total shock energy from ICDs is a significant predictor of mortality in recipients.
- Patients with pre-existing conditions like low LVEF or AF are particularly vulnerable to the adverse effects of high ICD shock energy.
Background:
Implantable Cardioverter-Defibrillator (ICD) shocks have been associated with mortality. However, no study has examined the relation between total shock energy and mortality. The aim of this study is to assess the association of total shock energy with mortality, and to determine the patients who are at risk of this association.
Methods:
Data from 316 consecutive patients who underwent initial ICD implantation in our hospital between 2000 and 2011 were retrospectively studied. We collected shock energy for 3 years from the ICD implantation, and determined the relation of shock energy on mortality after adjusting confounding factors.
Results:
Eighty-seven ICD recipients experienced shock(s) within 3 years from ICD implantation and 43 patients had died during the follow-up. The amount of shock energy was significantly associated with all-cause death [adjusted hazard ratio (HR) 1.26 (per 100 joule increase), p < 0.01] and tended to be associated with cardiac death (adjusted HR 1.30, p = 0.08). The survival rate of patients with high shock energy accumulation (≥182 joule) was lower (p < 0.05), as compared to low shock energy accumulation (<182 joule), likewise to no shock. Besides, the relation between high shock energy accumulation and all-cause death was remarkable in the patients with low left ventricular ejection fraction (LVEF ≤40%) or atrial fibrillation (AF).
Conclusions:
Increase of shock energy was related to mortality in ICD recipients. This relation was evident in patients with low LVEF or AF.
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