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Updated: Jun 12, 2026
A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Left ventricular ejection fraction for sudden death risk stratification and guiding implantable
Alfred E Buxton1, Kristin E Ellison, Peem Lorvidhaya
1Alpert Medical School of Brown University and Lifespan AcademicMedical Center, Providence, RI 02905. USA. alfred_buxton@brown.edu
Insights
Current guidelines for implantable cardioverter-defibrillators (ICDs) rely heavily on ejection fraction (EF). However, EF alone may not accurately identify all patients at risk for sudden cardiac death, necessitating a broader assessment.
Area of Science:
- Cardiology
- Electrophysiology
- Preventive Medicine
Background:
- Current guidelines for implantable cardioverter-defibrillators (ICDs) primarily use ejection fraction (EF) <30%-35% for primary prevention of sudden cardiac death.
- This guideline is based on randomized clinical trials that used EF as the primary endpoint to assess mortality reduction.
Purpose of the Study:
- To evaluate the limitations of using ejection fraction (EF) as the sole criterion for ICD implantation.
- To explore alternative prognostic markers for identifying patients at risk of sudden cardiac death.
Main Methods:
- Review of existing randomized clinical trials and prognostic studies.
- Analysis of limitations of ejection fraction (EF) in stratifying sudden cardiac death risk.
- Identification of alternative markers such as repolarization reserve and autonomic balance.
Main Results:
- Low EF (<30%-35%) identifies a population at increased risk, but not all patients with low EF are uniformly high-risk.
- Patients with EF >35% are not uniformly low-risk; some exhibit high risk based on other markers.
- A disconnect exists between low EF and the mechanisms underlying ventricular tachyarrhythmias.
Conclusions:
- Ejection fraction (EF) alone is insufficient for comprehensive risk stratification for sudden cardiac death in patients with coronary disease and nonischemic dilated cardiomyopathy.
- Further research into alternative markers like repolarization reserve and autonomic function is crucial for refining ICD implantation guidelines.
Abstract:
Current guidelines for use of implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden death in patients with coronary disease and nonischemic dilated cardiomyopathy are based primarily on ejection fraction (EF) <30%-35%. The origin of this is based on EF as the common variable in several randomized clinical trials evaluating the ability of ICDs to reduce mortality. However, although low EF identifies one patient population at relatively increased risk for sudden death, there are a number of limitations to use of EF as the primary indication for ICD. Patients with low EF are not uniform with regard to other prognostic markers, and not all are at high risk for sudden death. Conversely, although patients with EF >35% as a group are at lower risk for sudden death, these patients are not uniform with regard to other prognostic variables. A variety of tests, including measures of reduced repolarization reserve and measures of altered sympathetic/parasympathetic balance, have identified patients with EF >35% at relatively high risk for sudden death. One explanation for this "disconnect" is that there is no evidence of any direct mechanistic link between low EF and mechanisms responsible for ventricular tachyarrhythmias.
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