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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
Time dependence of defibrillator benefit after coronary revascularization in the Multicenter Automatic Defibrillator
Ilan Goldenberg1, Arthur J Moss, Scott McNitt
1Cardiology Unit, Department of Medicine, University of Rochester Medical Center, Rochester, New York 14642, USA. ilan.goldenberg@heart.rochester.edu
Insights
The implantable cardioverter-defibrillator (ICD) provides survival benefits for ischemic left ventricular dysfunction patients more than six months after coronary revascularization (CR). Early ICD implantation (≤6 months post-CR) shows no benefit, likely due to lower sudden cardiac death risk.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Surgery
Background:
- Implantable cardioverter-defibrillators (ICDs) improve survival in high-risk cardiac patients.
- The CABG-Patch trial showed no survival benefit with prophylactic ICD implantation during coronary artery bypass grafting (CABG).
Purpose of the Study:
- To assess the time-dependent effect of coronary revascularization (CR) on implantable cardioverter-defibrillator (ICD) benefit and sudden cardiac death (SCD) risk in patients with ischemic left ventricular dysfunction.
Main Methods:
- Analysis of outcomes based on time elapsed since coronary revascularization (CR) in 951 patients from the Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II.
- Comparison of ICD therapy versus conventional therapy, examining hazard ratios (HR) and p-values.
Main Results:
- ICD therapy showed a significant survival benefit (HR=0.64, p=0.01) in patients implanted >6 months after CR.
- No survival benefit was observed for ICD therapy in patients implanted ≤6 months after CR (HR=1.19, p=0.76).
- In the conventional therapy group, cardiac death risk increased significantly with time from CR, with a six-fold rise in SCD risk >6 months post-CR.
Conclusions:
- ICD efficacy in ischemic left ventricular dysfunction is time-dependent following CR.
- Significant life-saving benefits of ICDs are evident when implanted >6 months after CR.
- The lack of early benefit may be attributed to a lower risk of SCD within the first six months post-CR.
Objectives:
The study was designed to assess the effect of elapsed time from coronary revascularization (CR) on the benefit of the implantable cardioverter-defibrillator (ICD) and the risk of sudden cardiac death (SCD) in patients with ischemic left ventricular dysfunction.
Background:
The ICD improves survival in appropriately selected high-risk cardiac patients by 30% to 54%. However, in the Coronary Artery Bypass Graft (CABG)-Patch trial no evidence of improved survival was shown among a similar population of patients in whom an ICD was implanted prophylactically at the time of elective CABG.
Methods:
The outcome by time from CR was analyzed in 951 patients in whom a revascularization procedure was performed before enrollment in the Multicenter Automatic Defibrillator Implantation Trial (MADIT)-II.
Results:
The adjusted hazard ratio (HR) of ICD versus conventional therapy was 0.64 (p = 0.01) among patients enrolled more than six months after CR, whereas no survival benefit with ICD therapy was shown among patients enrolled six months or earlier after CR (HR = 1.19; p = 0.76). In the conventional therapy group, the risk of cardiac death increased significantly with increasing time from CR (p for trend = 0.009), corresponding mainly to a six-fold increase in the risk of SCD among patients enrolled more than six months after CR.
Conclusions:
In patients with ischemic left ventricular dysfunction, the efficacy of ICD therapy after CR is time dependent, with a significant life-saving benefit in patients receiving device implantation more than six months after CR. The lack of ICD benefit when implanted early after CR may be related to a relatively low risk of SCD during this time period.
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