Outcomes after Implantable Cardioverter-Defibrillator Generator Replacement for Primary Prevention of Sudden Cardiac Death

Malini Madhavan, Jonathan W. Waks, Paul A. Friedman, Daniel B. Kramer, Alfred E. Buxton, Peter A. Noseworthy, Ramila A. Mehta, David O. Hodge, Angela Y. Higgins, Tracy L. Webster, Chance M. Witt, Yong Mei Cha, Bernard J. Gersh

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Background-The effectiveness of implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden death in patients with an ejection fraction (EF) ≤35% and clinical heart failure is well established. However, outcomes after replacement of the ICD generator in patients with recovery of EF to >35% and no previous therapies are not well characterized. Methods and Results-Between 2001 and 2011, generator replacement was performed at 2 tertiary medical centers in 253 patients (mean age, 68.3±12.7 years; 82% men) who had previously undergone ICD placement for primary prevention but subsequently never received appropriate ICD therapy. EF had recovered to >35% in 72 of 253 (28%) patients at generator replacement. During median (quartiles) follow-up of 3.3 (1.8-5.3) years after generator replacement, 68 of 253 (27%) experienced appropriate ICD therapy. Patients with EF ≤35% were more likely to experience ICD therapy compared with those with EF >35% (12% versus 5% per year; hazard ratio, 3.57; P=0.001). On multivariable analysis, low EF predicted appropriate ICD therapy after generator replacement (hazard ratio, 1.96 [1.35-2.87] per 10% decrement; P=0.001). Death occurred in 25% of patients 5 years after generator replacement. Mortality was similar in patients with EF ≤35% and >35% (7% versus 5% per year; hazard ratio, 1.10; P=0.68). Atrial fibrillation (3.24 [1.63-6.43]; P<0.001) and higher blood urea nitrogen (1.28 [1.14-1.45] per increase of 10 mg/dL; P<0.001) were associated with mortality. Conclusions-Although approximately one fourth of patients with a primary prevention ICD and no previous therapy have EF >35% at the time of generator replacement, these patients continue to be at significant risk for appropriate ICD therapy (5% per year). These data may inform decisions on ICD replacement.

Original languageEnglish (US)
Article numbere003283
JournalCirculation: Arrhythmia and Electrophysiology
Issue number3
StatePublished - Mar 1 2016


  • cardiomyopathy
  • death, sudden
  • defibrillators, implantable
  • follow-up studies
  • left ventricular ejection fraction
  • primary prevention
  • shock

ASJC Scopus subject areas

  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)


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