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Q: What is the SCD-HeFT Trial?
SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) is a placebo-controlled, randomized clinical trial sponsored by the National Institutes of Health to study the use of implantable defibrillators in patients with mild to moderate heart failure, an ejection fraction of 35% or less, and no previous life-threatening arrhythmic episode.
Thus, the primary purpose of this trial was to determine the efficacy of ICDs as a “primary prevention” therapy. The study has three arms: ICD arm, drug arm (amiodarone), and the control group, with the patients divided equally in each group. All patients in each group received optimal conventional heart failure therapy (ACE inhibitors, beta-blockers, etc.)
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Q: What is the objective of the trial?
The objective of the trial is to answer the question: “Will amiodarone and/or an ICD improve survival compared to placebo?”
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Q: What is the primary endpoint?
The primary endpoint is all-cause reduction in mortality. The study is powered to detect a 25% overall reduction in mortality with a minimum follow-up of 2.5 years, or 30 months ( = 0.025).
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Q: What are the secondary endpoints?
The secondary endpoints include: cause-specific deaths (arrhythmic and non-arrhythmic), quality of life, cost-effectiveness and the effect of T-wave alternan (TWA) testing.
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Q: How many patients are enrolled in this trial, and at how many clinical centers?
There are 2,521 patients enrolled in the trial, at 148 centers across the U.S., Canada (10), and New Zealand (1).
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Q: When did the trial start and end?
The first SCD-HeFT enrollments occurred in September 1997 and full enrollment was achieved in July 2001. The follow-up period is for a minimum of 30 months. The study closed on October 31, 2003. Preliminary results were announced at the American College of Cardiology (ACC) annual scientific sessions in March 2004; the first article to be published appeared in the New England Journal of Medicine on January 20, 2005.
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Q: Who are the principal investigators of this trial?
The study director is Dr. Gust Bardy, Seattle Institute for Cardiac Research/University of Washington. Co-principal investigators are Dr. Kerry Lee (statistician), Duke University College of Medicine; and Dr. Daniel Mark (economic and QOL analysis), Duke University College of Medicine.
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Q: How does this trial differ from other recent heart failure trials?
SCD-HeFT is the seminal ICD clinical study for primary prevention. Most previous heart failure trials studied the effects of cardiac resynchronization therapy (with or without ICD backup) on Class III and IV (moderate to severe) heart failure patients and had follow-up periods of less than two years. These studies provided conclusive evidence that CRT improves quality of life, exercise capacity and heart function, as well as a mortality benefit in CRT-D patients.
SCD-HeFT will provide additional information about the effects of ICD therapy on mortality in heart failure patients and further sub-analysis on ischemic and non-ischemic patients. In addition to being the largest ICD trial ever, SCD-HeFT also is the only ICD trial with a large Class II patient population, and a control group that is more than twice as big as any previous trial.
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Q: What does the term "primary prevention" mean?
Primary prevention refers to patients who have not yet had an incidence or episode of a particular medical condition – in this case an abnormally rapid heart rhythm known as ventricular tachycardia (VT) or ventricular fibrillation (VF), often leading to sudden cardiac arrest (SCA) or sudden cardiac death (SCD). Secondary prevention refers to patients who have survived these conditions, and receive a particular therapy in response to the episode. Secondary prevention trials, such as AVID, CASH and CIDS, have shown a significant mortality benefit for patients who receive ICDs over those who receive just drug therapy. However, recent primary prevention trials (MADIT, MUSTT, and MADIT II) have shown that people who have not yet suffered SCA also benefit greatly from the protection of an ICD.
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Q: Why is SCD-HeFT so important as a primary prevention trial?
There are approximately 5 million patients with congestive heart failure in the U.S. This is the largest single population of patients who could benefit from primary prevention of sudden cardiac arrest. In fact, people with congestive heart failure suffer SCA at a rate 6-9 times that of the general population and over 450,000 people die from SCA each year in the U.S., more than AIDS, lung cancer and breast cancer combined. Positive results from the SCD-HeFT study will reinforce the need to provide “preventive” ICD protection for these patients and could lead to revised medical guidelines and Medicare reimbursement in this huge patient population.
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Q: How many SCD-HeFT patients have the same condition as MADIT II patients?
Approximately 30% of SCD-HeFT patients have similar characteristics as those in the MADIT II trial.
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Q: What Medtronic products were used in this trial?
Medtronic provided MicroJewel II (model 7223 CX) single chamber implantable cardioverter defibrillators for this trial.
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Q: What are the inclusion criteria for this trial?
Patients must have had Class II or III CHF, a left ventricular ejection fraction of 35% or less, ischemic or non-ischemic dilated cardiomyopathy (DCM), CHF for at least three months, be on the appropriate dosage of ACE inhibitors and beta-blockers, if tolerated, and be at least 18 years old.
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Q. How can awareness about SCA be raised?
Companies like Medtronic have begun a public awareness campaign to get out the word about sudden cardiac arrest and the effectiveness of ICDs in preventing it.
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