Applicability of a Risk Score for Prediction of the Long-Term (8-Year) Benefit of the Implantable Cardioverter-Defibrillator
Can patients who derive long-term survival benefit from implantable cardioverter-defibrillators (ICDs) be identified with a simple risk score?
The subjects of this study were 1,191 patients with prior infarction and ejection fraction ≤30% enrolled in the MADIT-II trial (Multicenter Automatic Defibrillator Implantation Trial II) and followed for a median of 7.6 years. The risk score assigned one point each for New York Heart Association class III-IV, age >70 years, blood urea nitrogen (BUN) >26 mg/dl, QRS >0.12 s, and atrial fibrillation (AF). The primary endpoint was all-cause mortality.
There were 345 patients in a low-risk group (risk score 0), 646 in an intermediate-risk group (risk score 1-2), and 200 patients in a high-risk group (risk score 3-5). At 8 years of follow-up, survival was significantly higher with than without an ICD among low- (75% vs. 58%, respectively) and intermediate-risk patients (47% vs. 31%, respectively), but not high-risk patients (19% vs. 17%, respectively).
A simple risk score identifies patients with prior infarction and low ejection fraction who do not derive a survival benefit from a prophylactic non-resynchronization ICD.
The simple risk score used in this study appears to be useful for improving the cost-effectiveness of ICDs for the primary prevention of sudden cardiac death in patients with prior infarction and poor left ventricular function. It may be justifiable to withhold an ICD in patients who meet the MADIT-II criteria, but who have a risk score of 3-5 (e.g., a patient who is 75 years old with a BUN of 30 mg/dl and AF). But if one of the risk factors is QRS >120 ms, a biventricular ICD still is appropriate.
Keywords: Follow-Up Studies, Ventricular Function, Left, Blood Urea Nitrogen, Risk Factors, New York, Primary Prevention, Heart Diseases, Heart Failure, Survival, Defibrillators, Implantable, Death, Sudden, Cardiac, Mitogen-Activated Protein Kinases
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