Key result
Appropriate ICD therapy was associated with increased mortality compared to no episodes, with hazard ratios of 1.46 for ATP-only, 2.11 for single shock, and 2.55 for multiple shocks.
Why the study?
Do ICD therapies (ATP or shocks) increase the risk of mortality in patients with ICDs?
Observational (n=2,255)
Do ICD therapies (ATP or shocks) increase the risk of mortality in patients with ICDs?
Hazard Ratio: 1.46 (95% CI 1.05–2.02)
p-value: p=0.023
Appropriate ICD therapies, including both ATP and shocks, are associated with an increased risk of all-cause mortality, whereas inappropriate therapies are not.
Appropriate ICD therapies may mark higher-risk patients; leaves open whether therapies are causal or prognostic markers.
BACKGROUND: Analyses from primary prevention trials on implantable cardioverter defibrillator (ICD) therapy have shown an association between shocks and increased mortality. Recent data suggest a similar association with antitachycardia pacing (ATP). OBJECTIVE: The OMNI study is an observational study of pacemaker and ICD use. We aim to examine associations between ICD therapies and mortality in this setting. METHODS: A total of 2,255 OMNI patients with ICDs were included. Treated episodes were classified as appropriate or inappropriate. Patients were assigned into 1 of 3 groups depending on whether the episode required ATP only, single shock, or multiple shocks, and then followed for all-cause mortality. Additionally, we aimed to determine the frequency with which inappropriate ATP precipitated ventricular arrhythmias that led to shock, since this has been suggested as a mechanism of harm. RESULTS: Over a mean follow-up of 39 ± 19 months, there were a total of 470 deaths (21%). Compared to patients with no treated episodes, patients with appropriate therapy had greater risk of death. Hazard ratios were 1.46 (95% confidence interval [CI] 1.05-2.02; P = 0.023) for the ATP-only group, 2.11 (95% CI 1.51-2.96; P < 0.001) for the single-shock group, and 2.55 (95% CI 1.43-4.57; P = 0.002) for the multishock group. There was no significant association between any type of inappropriate therapy and increased mortality. We identified only 7 instances of inappropriate ATP precipitating ventricular arrhythmia resulting in shock. CONCLUSIONS: Patients receiving appropriate therapy of all types had increased mortality compared to those with no episodes. Furthermore, inappropriate ATP rarely precipitates ventricular arrhythmias.
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Sun et al. (2015) conducted an observational in Patients with implantable cardioverter defibrillators (ICDs) (n=2,255). Appropriate ICD therapy (ATP only, single shock, or multiple shocks) vs. No treated episodes was evaluated on All-cause mortality (HR 1.46, 95% CI 1.05-2.02, p=0.023). Appropriate ICD therapy was associated with increased mortality compared to no episodes, with hazard ratios of 1.46 for ATP-only, 2.11 for single shock, and 2.55 for multiple shocks.
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