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Antiarrhythmic drug use in the implantable defibrillator arm of the Antiarrhythmics Versus Implantable Defibrillators
J S Steinberg1, J Martins, S Sadanandan
1Division of Cardiology, St Luke's-Roosevelt Hospital Center, New York, NY 10025, USA. jss7@columbia.edu
Insights
Antiarrhythmic drugs (AADs) are often added to implantable cardioverter-defibrillators (ICDs) for ventricular arrhythmias. AADs successfully reduced frequent ICD shocks in 18% of patients, extending time to the first event.
Area of Science:
- Cardiology
- Electrophysiology
- Pharmacology
Background:
- Implantable cardioverter-defibrillators (ICDs) are used for ventricular arrhythmias, but concomitant antiarrhythmic drug (AAD) use is common.
- The clinical benefit and necessity of AADs with ICDs remain uncertain, with potential for adverse interactions.
Purpose of the Study:
- To prospectively evaluate the need for and effects of adding AADs in patients with ICDs.
- To analyze the reasons for and outcomes of AAD use in a defined cohort.
Main Methods:
- Patients in the ICD arm of the AVID study were monitored for AAD addition post-discharge.
- Protocols strictly regulated AAD initiation; timing, reasons, and effects on arrhythmia recurrence were analyzed.
- Exclusion criteria included pre-discharge AAD requirement or absence of ventricular arrhythmia before AAD initiation.
Main Results:
- 18% of 461 patients required AADs, primarily for frequent ICD shocks (64%).
- Amiodarone was the most common AAD (42%). Predictors included lower ejection fraction and specific arrhythmia types.
- AAD use reduced the 1-year event rate from 90% to 64% and extended time to first event; ICD therapy events decreased by 1.4 per patient.
Conclusions:
- Most patients receiving ICDs for ventricular tachycardia/fibrillation do not require AADs.
- AADs are most frequently added to manage frequent ICD shocks, demonstrating significant success in reducing them.
Background:
Previous retrospective or observational series suggest that many patients with an implantable cardioverter-defibrillator (ICD) will be treated with antiarrhythmic drugs (AADs) to modify the frequency or manifestation of recurrent ventricular arrhythmias. The relative clinical benefit, however, is uncertain, and deleterious interactions can occur. The objective of this clinical investigation was to study the need for, and effects of, concomitant AAD use with the ICD in a prospectively defined cohort.
Methods:
All patients randomly assigned to the ICD arm of the Antiarrhythmics Versus Implantable Defibrillators (AVID) study were followed for the addition of class I or III AADs ("crossover") after hospital discharge. Addition of AADs was strictly regulated by AVID protocol. The timing and reasons for crossover and the effects on ventricular arrhythmia recurrence were analyzed. Patients were excluded if they required AADs before hospital discharge after index arrhythmias or if they had no ventricular arrhythmia before initiation of AADs.
Results:
After a median follow-up of 135 days, 81 (18%) of the 461 eligible patients required AADs and formed the crossover group. The primary reason for crossover was frequent ICD shocks in 64% of patients. The most common AAD selected was amiodarone (in 42%). Independent predictors of crossover were lower ejection fraction, absence of ventricular fibrillation, or presence of nonsyncopal ventricular tachycardia at presentation, prior unexplained syncope, female sex, and history of cigarette smoking. Before AAD use, the 1-year arrhythmia event rate was 90%; after AAD, the event rate was only 64% (P =.0001). The time to first event was extended from 3.9 +/- 0.7 months to 11.2 +/- 1.8 months. There were 1.4 +/- 3.7 fewer ICD therapy events (P =.005) after crossover, predominantly accounted for by reduction in shocks rather than antitachycardia pacing therapies.
Conclusions:
The majority of patients who receive ICDs for sustained ventricular tachycardia or ventricular fibrillation can be treated without AADs. Most commonly, AADs are added to combat frequent ICD shocks, which are successfully reduced by AAD therapy.
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