August 17, 2015
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LVEF reassessments may help identify patients eligible for ICD replacement

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Mortality and appropriate shocks for ventricular tachyarrhythmias were less common among patients who exhibited improved left ventricular ejection fraction nearly 5 years after receiving an implantable cardioverter defibrillator device, according to recent study findings.

The findings indicate that frequent LVEF assessments may help to identify patients who would potentially benefit from generator replacement, the researchers wrote. 

“Our results highlight an urgent need to refine the risk–benefit assessment in people repeatedly over the course of their treatment, and not just at the time of device implantation,” Alan Cheng, MD, a cardiac electrophysiologist and associate professor of medicine at Johns Hopkins University School of Medicine, said in a press release. “Determining if patients with defibrillators whose hearts get better over time may be better off without the device is just as important as determining who needs a defibrillator in the first place.”

The researchers analyzed data on 538 patients (mean age, 58.9 years; 70.1% men) from the PROSE-ICD cohort who received a primary prevention ICD between 2003 and 2013. All patients had at least one LVEF reassessment, mainly through echocardiography (80.6% of measurements), with follow-up conducted in person or over the telephone every 6 months and after any patient-perceived ICD therapy.

During a mean follow-up of 4.9 years, 40% of patients had improved LVEF and 25% had LVEF greater than 35%. These patients were more likely to be younger, to have lower LVEF baseline measures and to have received a cardiac resynchronization therapy defibrillator compared with patients who had reduced (13%) or unchanged (47%) LVEF at follow-up.

All-cause mortality and appropriate shock were inversely associated with changes in LVEF, which is consistent with smaller studies, according to the researchers.

Cheng and colleagues also conducted a shock analysis in 464 patients who were reassessed at least once before their first appropriate shock or before the end of the study period. During a mean follow-up of 2 years since the last available assessment, 96 deaths and 27 shocks occurred, four of which occurred in patients with LVEF greater than 35%. Those with improved LVEF had reduced risk for mortality (HR = 0.33; 95% CI, 0.18-0.59) and appropriate shock (HR = 0.29; 95% CI, 0.11-0.78) compared with patients whose LVEF did not change. However, since the risk for shock was not eliminated, “improvements in LVEF alone may not be enough to warrant deferring ICD generator exchange,” the researchers wrote.

They concluded that larger studies with more frequent LVEF reassessments are needed to determine whether patients with improved ejection fraction may benefit from generator replacement.

In a related editorial, Kristen K. Patton, MD, from the department of medicine at University of Washington, Seattle, also called for further research. She said LVEF may be inadequate in identifying patients eligible for replacement, and other markers must be considered.

“Human brains are not well designed to confront uncertainty,” she wrote. “It is in this evolutionary and cultural context that physicians are asked to help patients decide if the benefit of continued ICD therapy is worth it, especially given the risks. For some, ICD therapy results in gradual accumulation of complications; for others, a life is saved. The perennial problem is in identifying which patient might be in which category.” – by Stephanie Viguers

Disclosure: The researchers and Patton report no relevant financial disclosures.