Implantable cardioverter-defibrillator (ICD) implantation is standard of care for patients who have survived life threatening ventricular tachyarrhythmias (LTVA). ICD shocks predict future adverse events in patients with ICD implantation for primary prevention. However, the role of ICD shocks in prediction of adverse events in a secondary prevention population is unknown. The Antiarrhythmics Versus ICDs (AVID) Trial (n=1016) was a randomized controlled trial comparing ICD (n=507) and antiarrhythmic drugs (n=509) in the treatment of patients with LTVA.

Mean follow-up duration was 916 ± 471 days. We analyzed the ICD arm of the AVID trial using the NHLBI limited access dataset. ICD shocks were categorized as appropriate if underlying rhythm triggering the shock was ventricular tachycardia or ventricular fi brillation. All other ICD shocks were considered as inappropriate. Data on ICD therapy was available for 420 patients. Any shock (n=380), any appropriate (n=296) or any inappropriate (n=72) shock was not associated with increased all cause, cardiac or arrhythmic mortality. However any appropriate shock was associated with increased LTVA. In conclusion, ICD shocks do not confer increased risk of death on follow up in LTVA survivors. Use of ICD shocks as surrogate marker for adverse outcomes is not viable in secondary prevention patients.

Heart failure patients with decreased ejection fraction are at increased risk of sudden death due to ventricular arrhythmias. Since its introduction in 1980, use of implantable cardioverterdefibrillator (ICD) as a therapeutic modality has been effective in heart failure patients treating malignant arrhythmias for both primary and secondary prevention. Device therapy can be classified as appropriate and inappropriate shocks. Appropriate shock includes shock therapy for LTVA like ventricular tachycardia (VT) and ventricular fibrillation (VF). Inappropriate shock includes shock therapy for supra ventricular arrhythmias including atrial fibrillation (AF), atrial flutter etc or any other inappropriate sensing.

Prior studies have reported that appropriate and inappropriate shock therapy identifies ICD recipients at increased risk of mortality as compared to those who received no shocks in a primary prevention cohort. No prior studies have detailed the risk of mortality after ICD shock therapy in a secondary prevention population. We hypothesized that similar effect of ICD shocks could also be observed in a secondary prevention population. For this purpose we decided to investigate the Anti-arrhythmics Versus Implantable Defibrillators (AVID) trial, 4 which is the largest secondary prevention trial.

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ISSN: 2155-9880

Current Issue: Volume 11, Issue 6

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