Abstract 16465: Once an Implantable Defibrillator, Always an Implantable Defibrillator?
Introduction: A subset of patients with primary prevention implantable defibrillators (ICD) and severe LV systolic dysfunction are observed to undergo improvement/normalization of LV systolic function over time. Should these patients continue to have indwelling implantable defibrillators?
Methods: From a community-based study we analyzed the temporal trends in LV ejection fraction (EF) among patients with established severe LV systolic dysfunction (LVSD) who eventually suffered sudden cardiac arrest (SCA). SCA cases with coronary artery disease (CAD) were compared to controls with CAD from the same geographical region. LVEF was assessed from echocardiogram and categorized as normal (EF ≥ 55%), mild-moderate dysfunction (EF = 36-54%) and severe LV dysfunction (EF ≤ 35%).
Results: A total of 111 SCA cases (age 68.9±13.7 years, 75% male) with more than one echocardiogram performed prior to, and unrelated to each cardiac arrest were included in this analysis. The initial distribution of LVSD was: normal 49 (44%), mild-moderate 31 (28%), severe 31 (28%). Overall there was a change from the baseline ejection fraction in 33 cases (30%) - improvement in a total of 15 and worsening in 18 cases. Out of the 31 cases with severe LVSD, ejection fraction improved in 11 (35%) subjects over a period of 35±22 months (median 37, range 4-60 months). In 7 subjects EF improved to mild-moderately decreased (mean 39±19, median 46, range 6-60 months) and in 4 subjects to normal (mean 27±26, median 22, range 4-60 months).
Conclusions: Among patients with severe LV dysfunction there is a distinct subgroup (one-third) that undergoes improvement/normalization of LV systolic function with continued increased SCA risk. These findings have implications for clinical decision making in ICD patients especially at the time of generator replacement; and warrant evaluation in other populations.
- © 2011 by American Heart Association, Inc.