Ejection Fraction and QRS Width as Predictors of Event Rates in Patients with Implantable Cardioverter Defibrillators
Objectives: The Multicenter Automatic Defibrillator Implantation Trial II in 2002 recommended implantable cardioverter defibrillators (ICDs) prophylactically for all patients with a prior myocardial infarction and ejection fraction (EF) of 30% or less. In June of 2003, the Centers for Medicare and Medicaid Services approved reimbursement for ICD placement in patients with an EF of 30% or less who have a QRS interval greater than 120 ms. The purpose of this study was therefore to determine the value of QRS duration in predicting the occurrence of ventricular arrhythmias within the first year after ICD implantation. These ICDs were placed over the past 5 years for various indications.
Methods: EF cut points of 30% or less and 31% or greater and QRS duration of 120 ms or less and 121 ms or greater were used to assess the risk of events.
Results: There was a significant increase in events in subjects with EF of 30% or less, compared with patients with EF of 31% or greater (P < 0.05), and there was a trend toward increased likelihood of arrhythmias in patients with widened QRS width.
Conclusions: This study confirms the conclusion of the Multicenter Automatic Defibrillator Implantation Trial II and implies that the Centers for Medicare and Medicaid Services criteria for reimbursement may not be scientifically valid.
* Widened QRS duration does not predict the likelihood of ventricular arrhythmias.
* Decreased ejection fraction predicts increases in ventricular arrhythmias.
* Combining widened QRS duration and decreased ejection fraction does not improve the predictability of ventricular arrhythmias.
* Increasing QRS width is associated with a progressive decrease in ejection fraction.
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