An examination of the benefit of preventive placement of implantable cardioverter-defibrillators (ICDs) in patients with a less severe level of heart failure, a group not well represented in clinical trials, finds significantly better survival at three years than that of similar patients with no ICD, according to a study in the June 4 issue of JAMA.
Although clinical trials have established the ICD as the best currently available therapy to prevent sudden cardiac death in patients with heart failure, some uncertainties remain regarding preventive use of ICDs in patients seen in clinical practice. Of patients enrolled in randomised clinical trials of prophylactic (preventive) ICDs, the median left ventricular ejection fraction (LVEF; the percentage of blood that is pumped out of a filled ventricle as a result of a heartbeat) is well below 30%. Because a large number of prophylactic ICDs in the United States are implanted in patients with an left ventricular ejection fraction between 30% and 35%, understanding outcomes associated with the ICDs in such patients is important. The Centers for Medicare & Medicaid Services have designated these patients as an important subgroup for whom more data on ICD effectiveness are needed, according to background information in the article.
Sana M Al-Khatib, of the Duke University Medical Center, Durham, USA, and colleagues compared survival in Medicare beneficiaries in the National Cardiovascular Data Registry ICD registry with a left ventricular ejection fraction between 30% and 35% who received an ICD during a heart failure hospitalisation with similar patients in the Get With The Guidelines-Heart Failure database with no ICD. The analysis was repeated in patients with a left ventricular ejection fraction less than 30%.
There were no significant differences in the baseline characteristics of the matched groups (n = 408 for both groups). At one year, 24.5% of ICD patients died vs 24.9% of non-ICD patients. At three years, 51.4% of the ICD patients died, compared with 55% of the non-ICD patients, a significantly lower risk of death among patients with a left ventricular ejection fraction between 30% and 35% who received an ICD. Presence of an ICD also was associated with better survival in patients with a left ventricular ejection fraction less than 30% (three-year mortality rates: 45% vs 57.6%).
The authors write that although the difference in absolute risk by three years was not large (3.6%), it was significant and close in magnitude to what was observed in other clinical trials of prophylactic ICDs. “These results support guidelines’ recommendations to implant a prophylactic ICD in eligible patients with a left ventricular ejection fraction of 35% or less.”