Related Experiment Video
Updated: Jul 8, 2026
A New Single Chamber Implantable Defibrillator with Atrial Sensing: A Practical Demonstration of Sensing and Ease of Implantation
Published on: February 28, 2012
Risk stratification for primary implantation of a cardioverter-defibrillator in patients with ischemic left
Ilan Goldenberg1, Anant K Vyas, W Jackson Hall
1Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA. Ilan.Goldenberg@heart.rochester.edu
Insights
A new risk score helps identify patients with low ejection fraction who benefit most from an implantable cardioverter-defibrillator (ICD). The score shows ICDs are most effective in intermediate-risk patients, not those at very low or very high risk.
Area of Science:
- Cardiology
- Medical Devices
- Clinical Risk Stratification
Background:
- Current guidelines recommend implantable cardioverter-defibrillators (ICDs) for primary prevention in patients with low ejection fraction (EF).
- The uniform benefit of ICDs in this low EF population is uncertain.
Purpose of the Study:
- To develop a simple clinical risk stratification score for primary ICD therapy.
- To assess ICD benefit across different risk categories in patients with low EF.
Main Methods:
- A best-subset proportional-hazards regression model was used.
- The analysis included patients from the Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II conventional therapy arm, excluding very high-risk (VHR) patients.
- Risk score categories were defined, and ICD benefit was evaluated within these strata and in VHR patients.
Main Results:
- A 5-factor risk score was developed (NYHA class, age, BUN, QRS duration, atrial fibrillation).
- Mortality rates varied significantly by risk score in the conventional therapy group (8% for 0 factors, 28% for >=1 factor, 43% for VHR).
- ICD therapy reduced mortality by 49% in patients with >=1 risk factor, but showed no benefit in patients with 0 risk factors or VHR patients.
Conclusions:
- A U-shaped pattern of ICD efficacy was observed in the low EF population.
- Intermediate-risk patients (>=1 risk factor) demonstrated the most pronounced benefit from ICD therapy.
- ICD efficacy was attenuated in both lower-risk (0 risk factors) and higher-risk (VHR) patient subsets.
Objectives:
The study was designed to develop a simple risk stratification score for primary therapy with an implantable cardioverter-defibrillator (ICD).
Background:
Current guidelines recommend primary ICD therapy in patients with a low ejection fraction (EF). However, the benefit of the ICD in the low EF population may not be uniform.
Methods:
Best-subset proportional-hazards regression analysis was used to develop a simple clinical risk score for the end point of all-cause mortality in patients allocated to the conventional therapy arm of MADIT (Multicenter Automatic Defibrillator Implantation Trial)-II after excluding a pre-specified subgroup of very high-risk (VHR) patients (defined by blood urea nitrogen [BUN] >or=50 mg/dl and/or serum creatinine >or=2.5 mg/dl). The benefit of the ICD was then assessed within risk score categories and separately in VHR patients.
Results:
The selected risk score model comprised 5 clinical factors (New York Heart Association functional class >II, age >70 years, BUN >26 mg/dl, QRS duration >0.12 s, and atrial fibrillation). Crude mortality rates in the conventional group were 8% and 28% in patients with 0 and >or=1 risk factors, respectively, and 43% in VHR patients. Defibrillator therapy was associated with a 49% reduction in the risk of death (p < 0.001) among patients with >or=1 risk factors (n = 786), whereas no ICD benefit was identified in patients with 0 risk factors (n = 345; hazard ratio 0.96; p = 0.91) and in VHR patients (n = 60; hazard ratio 1.00; p > 0.99).
Conclusions:
Our data suggest a U-shaped pattern for ICD efficacy in the low-EF population, with pronounced benefit in intermediate-risk patients and attenuated efficacy in lower- and higher-risk subsets.
Related Concept Videos
01:29Cardiomyopathy V: Interprofessional Care
01:30Heart Failure IV: Classification and Diagnostic Evaluation
01:30Cardiomyopathy II: Dilated Cardiomyopathy
01:25Cardiomyopathy I: Introduction and Classification
01:29Cardiomyopathy III: Hypertrophic Cardiomyopathy
01:17Ischemic Heart Disease: Overview
Atherosclerosis, the primary malefactor, orchestrates this dangerous condition. It manifests as the accumulation of fatty deposits, akin to insidious plaques, within arterial walls. As time elapses, these plaques metamorphose, hardening and narrowing...