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Other primary prevention trials-what is clinically and economically necessary?
1Good Samaritan Hospital, Los Angeles, California, USA. dcannom@lacard.com.
Insights
Primary prevention implantable cardioverter defibrillator (ICD) trials are evaluating high-risk patients with low ejection fraction. Results will clarify which patients benefit most from ICD therapy, improving cardiac care.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Primary prevention implantable cardioverter defibrillator (ICD) trials are crucial for defining their role in high-risk patients.
- High-risk patients are typically identified by low ejection fraction (EF), with electrical markers also under evaluation.
Purpose of the Study:
- To evaluate the effectiveness of ICD therapy in high-risk patients with coronary or idiopathic cardiomyopathy and EF ≤ 35%.
- To compare ICD therapy against no antiarrhythmic drug therapy in these patient groups.
Main Methods:
- Randomized controlled trials (e.g., SCD-HEFT, MADIT II, CABG-PATCH substudy) are analyzing patients with EF ≤ 35%.
- Maximal congestive heart failure therapy (ACE inhibitors, beta-blockers) is administered to both arms.
Main Results:
- Ongoing trials aim to determine which high-risk patient groups, if any, benefit from ICD implantation.
- A national registry for ICD firing rates is proposed for high-risk patients with specific diagnoses where large trials are infeasible.
Conclusions:
- Further data from ongoing trials are needed to establish definitive guidelines for ICD use in primary prevention.
- Registries are essential for understanding ICD performance in rare high-risk patient populations.
Abstract:
There are a number of important primary prevention implantable cardioverter defibrillator (ICD) trials underway which will help define the role of the ICD in high risk patients. High risk is defined by low ejection fraction, although a number of electrical markers (e.g., the signal averaged ECG and invasive electrophysiologic test) are also under evaluation. The trials currently underway (including SCD-HEFT, MADIT II, and the CABG-PATCH substudy) are analyzing patients with either coronary or idiopathic cardiomyopathy who have an EF of 35% or under. Patients are randomized to either ICD therapy or no antiarrhythmic drug therapy. Maximal congestive heart failure therapy with ACE inhibitors and beta blockers is used in both arms of each trial. At the conclusion of these trials we should have a better understanding of which group of presumably high risk patients, if any, will benefit from the ICD. Another group of high risk patients that is being encountered more frequently: those who have a high risk diagnosis. These patients are present in such small numbers that a large randomized trial is impossible. As many of these patients are receiving ICDs, a national registry of firing rates will be helpful.