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A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Appropriate therapy but not inappropriate shocks predict survival in implantable cardioverter defibrillator patients
Wolfgang Dichtl1, Thomas Wolber, Ursula Paoli
1Clinic for Internal Medicine III/Cardiology, Medical University Innsbruck, Innsbruck, Austria. wolfgang.dichtl@uki.at
Insights
Inappropriate implantable cardioverter defibrillator (ICD) shocks do not impact patient survival. However, appropriate ICD therapy indicates worsening heart disease and requires further medical attention.
Area of Science:
- Cardiology
- Medical Devices
- Clinical Outcomes
Background:
- Inappropriate implantable cardioverter defibrillator (ICD) shocks may cause myocardial injury.
- The prognostic impact of ICD shocks on clinical outcomes is debated.
Purpose of the Study:
- To investigate the impact of appropriate and inappropriate ICD therapies on survival.
- To determine if ICD shock therapy itself worsens clinical outcomes.
Main Methods:
- Retrospective analysis of 1117 ICD recipients.
- Evaluation of appropriate and inappropriate ICD therapies and patient survival.
- Mean follow-up of 2.92 years.
Main Results:
- Appropriate therapy occurred in 27.7% (primary prevention) and 54.0% (secondary prevention) of patients.
- Inappropriate shock therapy occurred in 15.0% (primary) and 25.4% (secondary) of patients.
- Appropriate ICD therapy significantly impacted overall survival (P<0.0001); inappropriate shocks did not affect mortality.
Conclusions:
- Inappropriate ICD shocks do not negatively affect patient survival.
- Appropriate ICD therapy is a marker of underlying heart disease progression, not the shock itself.
- Physicians should consider additional treatment strategies when appropriate ICD therapy is delivered.
Background:
Inappropriate implantable cardioverter defibrillator (ICD) shocks have been linked to a worse clinical outcome due to direct myocardial injury.
Hypothesis:
The occurrence of ventricular tachyarrhythmia indicating progression of the underlying heart disease, but not the ICD shock itself, has prognostic impact in clinical routine.
Methods:
In a retrospective study, 1117 recipients of an ICD were analyzed with respect to appropriate and inappropriate therapies and survival.
Results:
During a mean follow-up of 2.92 years, appropriate therapy occurred in 27.7% and 54.0% of patients who had received an ICD for primary and secondary prevention of sudden cardiac death (SCD), respectively (P<0.0001). Inappropriate shock therapy occurred in 15.0% and 25.4% of patients who had received an ICD for primary and secondary prevention of SCD, respectively (P = 0.122). Appropriate ICD therapy had a strong impact on overall survival (P<0.0001), and this association was found both in primary (P<0.0001) and secondary (P = 0.002) prevention of SCD. Inappropriate ICD shocks had no impact on total mortality, neither in primary nor secondary prevention of SCD.
Conclusions:
Inappropriate shocks do not affect survival, in strong contrast to appropriate ICD therapy. Our study does not support the hypothesis that shock therapy in itself worsens clinical outcome. However, it confirms that appropriate ICD therapy is a warning sign and should prompt physicians to consider additional treatment strategies.
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