Survival After Implantable Cardioverter-Defibrillator Shocks.

Abstract

BACKGROUND:

There are conflicting data on the impact of implantable cardioverter-defibrillator (ICD) shocks on subsequent mortality.

OBJECTIVES:

The aim of this study was to determine whether the arrhythmic substrate leading to ICD therapy or the therapy itself increases mortality.

METHODS:

The study cohort included 5,516 ICD recipients who were enrolled in 5 landmark ICD trials (MADIT-II, MADIT-RISK, MADIT-CRT, MADIT-RIT, RAID). The authors evaluated the association of device therapy with subsequent mortality in 4 separate time-dependent models: model I, type of ICD therapy; model II, type of arrhythmia for which ICD therapy was delivered; model III, combined assessment of all arrhythmia and therapy types during follow-up; and model IV, incremental risk associated with repeated ICD shocks.

RESULTS:

When analyzed by the type of ICD therapy (model I), a first appropriate ICD shock was associated with increased risk of subsequent mortality with or without concomitant occurrence of inappropriate shock during follow-up (hazard ratio [HR]: 2.78 and 2.31; p < 0.001 and p = 0.12), whereas inappropriate shock alone was not associated with mortality risk (HR: 1.23; p = 0.42). Similarly, ICD therapy for ventricular tachycardia (VT) ≥200 beats/min or ventricular fibrillation (VF) (model II) was associated with increased risk of death with or without concomitant therapy for VT <200 beats/min (HRs: 2.25 and 2.62; both p < 0.001), whereas appropriate therapy for VT <200 beats/min or inappropriate therapy (regardless of etiology) did not reach statistical significance (all p > 0.10). Combined assessment of all therapy and arrhythmia types during follow-up (model III) showed that appropriate ICD shocks for VF, shocks for fast VT (≥200 beats/min) without prior antitachycardia pacing (ATP), as well as shocks for fast VT delivered after failed ATP, were associated with the highest risk of subsequent death (HR: all >2.8; p < 0.001). Finally, 2 or more ICD appropriate shocks were not associated with incremental risk to the first appropriate ICD shock (model IV).

CONCLUSION:

The combined data from 5 landmark ICD trials suggest that the underlying arrhythmic substrate rather than the ICD therapy is the more important determinant of mortality in ICD recipients.

• Authors: Mehmet K Aktaş, Arwa Younis, Wojciech Zareba, Valentina Kutyifa, Helmut Klein, James P Daubert, Mark Estes, Scott McNitt, Bronislava Polonsky, Ilan Goldenberg
• Journal: Journal of the American College of Cardiology (J Am Coll Cardiol) Vol. 77 Issue 20 Pg. 2453-2462 (05 25 2021) ISSN: 1558-3597 [Electronic] United States
• PMID: 34016257 (Publication Type: Journal Article, Multicenter Study, Randomized Controlled Trial, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Topics

• Aged
• Cohort Studies
• Defibrillators, Implantable (adverse effects)
• Female
• Humans
• Male
• Middle Aged
• Tachycardia, Ventricular (mortality, therapy)