Abstract 11435: ICD Patients Whose Ejection Fraction Improves Above 35% with Medical Therapy are Still at Risk for Appropriate Shocks and Therapy
Background: Implantable cardioverter-defibrillators (ICD) are indicated in patients with left ventricular ejection fraction (EF) < 35%. Little is known on the long-term, device-related outcomes of ICD patients whose EF improves above 35% with medical therapy. Practice guidelines do not provide any recommendation on the appropriate management of such patients when they present with elective replacement indicator (ERI), but do not qualify for ICD on the basis of the current EF. The aim of this study was to assess the predictors and examine the device follow-up in patients whose EF had improved at the time of ERI. We hypothesized that these patients would be unlikely to have appropriate shock or therapy during follow-up after generator change.
Methods: We included 106 consecutive patients who underwent an ICD generator change at the Minneapolis Veterans Affairs Medical center from 2006 to 2010. Patients with CRT were excluded. All patients had an echocardiogram at baseline and at the time of ICD generator change. EF improvement at the time of generator change was defined as EF >35% and increase in EF >10% from baseline.
Results: Average age of study patients was 69±11 years; 79% had ischemic cardiomyopathy and 58% had ICD for primary prevention of sudden cardiac death. Overall, 22 (21%) patients met the criteria for improved EF (age 68±10; 68% ischemic; 68% primary prevention). All baseline characteristics of the patients whose EF did or did not improve were similar, including EF (34% in both). However, at the time of ICD generator change, patients with improved EF were less symptomatic (p=0.002) had lower diuretic requirement (p=0.02) and had a higher EF (52±10% vs. 35±12%; p<0.0001). Of the 22 patients with improved EF, 6 (28%) had appropriate shock, 8 (36%) had appropriate therapy (shock and/or anti-tachycardia pacing) and 20 (91%) had non-sustained ventricular tachycardia (NSVT). Notably, 23% of the shocks, 27% of the therapies and 73% of the NSVT occurred after the generator change and improvement in EF.
Conclusions: ICD patients whose EF improves above >35% with medical therapy are still at risk for appropriate ICD shock and therapy. These findings have significant implications in the management of patients when their device is ERI.
- © 2011 by American Heart Association, Inc.