A systematic review and meta-analysis of six observational studies found that the use of implantable cardioverter-defibrillators (ICDs) was associated with a 39 percent relative reduction in mortality among advanced heart failure patients with left ventricular assist devices (LVADs).
However, the researchers noted that only 38 percent of the patients used ICDs. They also mentioned that patients who used continuous-flow LVADs did not have a significant improvement in survival when using ICDs.
Lead researcher Kairav Vakil, MD, of the University of Minnesota and Veterans Affairs Medical Center in Minneapolis, and colleagues published their results online in the Journal of the American College of Cardiology: Heart Failure on Sept. 26.
Previous studies found that LVADs significantly improved survival in patients with end-stage heart failure who were awaiting or were ineligible for cardiac transplantation, according to the researchers. They mentioned the estimated one-year survival rate was between 56 percent and 87 percent and the four-year survival rate was approximately 47 percent.
For this analysis, they searched the PubMED and Ovid databases for randomized or observational studies published from January 2000 through October 2015. The inclusion criteria included studies that enrolled at least 20 patients, compared LVAD-supported patients with and without ICDs and reported all-cause mortality and the estimate of relative risk or alternative measures of relative risk such as hazard ratio or odds ratio.
Only six trials with a total of 937 patients met the inclusion criteria. The studies were published between 2009 and 2015 and included one in Europe, four in the U.S. and one in Australia.
The mean age was 53 years old, and 80 percent of patients were male. In addition, 59 percent of patients took beta-blockers, 65 percent took ACE inhibitors, 44 percent took aldosterone receptor antagonist and 39 percent had continuous-flow LVADs.
During a mean follow-up period of seven months, 26 percent of patients died, including 16 percent in the ICD group and 32 percent in the no-ICD group. The use of an ICD was associated with a 16 percent absolute risk reduction and 39 percent relative risk reduction in all-cause mortality.
The incidence of infection was 6 percent in patients with ICDs and 18 percent in patients who did not have an ICD, which was a statistically significant difference.
Among the patients with continuous-flow LVADs, the all-cause mortality rates were 14 percent in the ICD group and 25 percent in the no-ICD group. The use of an ICD was associated with an 11 percent absolute risk reduction and a 24 percent relative risk reduction in all-cause mortality. However, the trend towards improved survival with ICDs was not statistically significant.
The researchers cited a few limitations of the study, including that the studies were retrospective and observational and subject to bias. In addition, 93 percent of the patients received an LVD as bridge-to-transplantation, so the results cannot be generalized to patients receiving destination therapy LVADs. They also could not determine the cause of death and did not have information on the burden of ventricular arrhythmias and its relationship to timing of LVAD implantation, ICD therapies and ICD programming.
“Despite the improved outcomes of patients with mechanical circulatory support systems over the last decade, survival for patients with LVADs is relatively poor,” the researchers wrote. “Whether ICDs improve survival in patients with LVADs has been a matter of controversy. Although the findings from the current systematic review favor the use of ICDs in patients with LVADs, randomized control clinical trials addressing this very important question are strongly warranted to improve future patient outcomes. It would be ideal for future randomized studies to examine the utility and timing of ICD implantation in patients with newer generation [continuous flow]-LVADs when used for both, bridge-to-transplantation and destination therapy.”