Nearly 90 percent of adults who were eligible for cardiac resynchronization therapy defibrillators (CRT-D) were implanted with the device, according to a retrospective registry study.

A multivariable analysis also found that black race and nonprivate insurance were associated with lower use of CRT-D. The researchers noted that there was significant hospital variation in CRT-D use, as well.

Lead researcher Lucas N. Marzec, MD, of the University of Colorado School of Medicine, and colleagues published their results online Jan. 25 in JAMA Cardiology.

The researchers analyzed the National Cardiovascular Data Registry Implantable Cardioverter Defibrillator Registry and identified 71,662 adults at 1,428 hospitals. All of the patients underwent primary prevention implantable cardioverter defibrillator (ICD) or CRT-D implantation from April to June 2014.

Of the patients eligible for CRT, 88.6 percent received a CRT-D device, while 62.8 percent met a class I indication for CRT and 37.2 percent met a class IIa indication for CRT.

The researchers mentioned that patient factors independently associated with a higher likelihood of CRT-D implantation included increasing age and increasing New York Heart Association class. They added that patient factors associated with a lower likelihood of CRT-D implantation included black race, nonprivate insurance (including Medicare and Medicaid), atrial fibrillation/flutter, non–left bundle branch block QRS morphology, ischemic heart disease, cerebrovascular disease, diabetes and current hemodialysis.

In addition, they noted that clinician factors independently associated with higher rates of CRT-D use included higher device implanting volume and electrophysiology-trained implanting operator.  Further, they said that hospitals without CABG capabilities were less likely to implant CRT-D.

The unadjusted median rate of CRT-D use was 89.2 percent, while the usage rate was 79.9 percent after researchers adjusted for patient, implanting operator and hospital characteristics.

The researchers cited a few limitations of the study, including that the registry did not contain data on patients who were eligible for ICD or CRT-D implantation but did not receive a device. They also could not account for the rate of optimal medical therapy, patient preference or other variables that could have affected the device choice. In addition, they noted that the analysis could be subject to residual confounding. Further, they could not account for cases in which the clinicians’ CRT choices conflicted with guidelines.

“We observed wide hospital-level variation in CRT-D use in guideline-eligible patients,” the researchers wrote. “Future work should address strategies to reduce disparities in the use of CRT-D and improve rates of CRT-D use at sites with low rates of CRT-D implantation in eligible patients.”