ICDs Linked to Increased Heart Failure Survival Rates

Implantable cardioverter defibrillator (ICD) devices are associated with improved survival among heart failure (HF) patients with a left ventricular ejection fraction (LVEF) of 30%–35%, according to a new study.

Researchers at the Duke Clinical Research Institute (DCRI; Durham, NC, USA) conducted a retrospective cohort study of Medicare beneficiaries with an LVEF between 30% and 35% registered in the US National Cardiovascular ICD registry that received an ICD during a HF hospitalization, and similar patients with no ICD. In all, there were 3,120 patients in 816 matched cohorts in the study group, and 4,578 patients in 2,176 matched cohorts in the control group. The primary outcome was all-cause mortality; data were obtained from Medicare claims through December 31, 2011.

The results showed that while there were no significant differences in the baseline characteristics of the matched groups, the risk of all-cause mortality in patients with an LVEF of 30%–35% and an ICD was significantly lower than that in matched patients without an ICD (3-year mortality rates of 51.4% versus 55%, respectively). Presence of an ICD also was associated with better survival in patients with an LVEF less than 30% (3-year mortality rates of 45% versus 57.6%, respectively). The study was published in the June 4, 2014, issue of the Journal of the American Medical Association (JAMA).

“Our findings fill an important gap in knowledge, as most randomized clinical trials of ICDs include heart failure patients with a median LVEF of well below 30%,” said lead author DCRI associate professor of medicine Sana Al-Khatib, MD, MHS. “Until now, the association between the ICD and improved outcomes in patients with a LVEF of 30%–35% was largely implied. Our results support current guidelines to implant prophylactic ICDs in patients with a LVEF of 35% or lower.”

LVEF is the measurement of how much blood is pumped out of the left ventricle of the heart with each contraction, and is usually expressed as a percentage. A normal LVEF ranges from 55%–70%, while an LVEF of less than 40% may confirm a diagnosis of HF. A LVEF of less than 35% increases the risk of an arrhythmia leading to sudden cardiac arrest or death, and an ICD may be recommended for these patients.

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