ICD implantation boosts survival after cardiac arrests with reversible causes
Current clinical guidelines recommend implantable cardioverter-defibrillators (ICDs) in survivors of sudden cardiac arrest (SCA), except when the cause of the SCA is deemed reversible. But a new study in Circulation: Arrhythmia and Electrophysiology demonstrates that many of these patients gain a survival benefit from ICDs as well.
“These results deserve further confirmation in a multicenter, prospective randomized controlled trial, as they have important and immediate clinical implications to patient care,” wrote lead author Adetola Ladejobi, MD, and colleagues.
The researchers evaluated the records of 1,433 patients who were discharged alive after SCA from hospitals in the University of Pittsburgh Medical Center from 2000 through 2012. Fifty-five percent of these patients were considered to have a reversible and correctable cause—defined as electrolyte or metabolic abnormalities, acute myocardial infarction (MI) or cardiac ischemia treated with coronary revascularization, recent initiation of an antiarrhythmic drug, illicit drug use or other reversible circumstances.
Over a mean follow-up of 3.8 years, ICD implantation was associated with a 39 percent lower mortality risk among SCA sufferers with a reversible cause. Notably, this relative survival benefit was 60 percent in those whose SCA wasn’t associated with MI or cardiac ischemia, while device implantation in the MI/ischemia group wasn’t linked to any benefit (hazard ratio: 1.04).
“After coronary revascularization, the benefit of ICD therapy may be significantly diluted as previously demonstrated in a randomized trial, particularly that the rates of target vessel reocclusion or revascularization have significantly improved over the years and are below 10 percent for both percutaneous coronary interventions and coronary bypass surgery,” Ladejobi et al. wrote. “Metabolic derangements and exposure to illicit drugs or antiarrhythmic medications are not as readily avoidable in future follow-up which is why ICD therapy may have more of an impact on survival in that setting.”
The authors noted ICDs are placed in about 40 percent of SCA survivors who have a reversible cause “without clear evidence to guide this decision.” Defining what is reversible and determining the exact cause of SCA is often difficult, although the researchers clearly outlined the definitions they used in the study.
In an accompanying editorial, two cardiologists from the University of Washington pointed out a randomized trial might be expensive and logistically challenging for SCA patients with ischemia or MI. They said a prospective registry with careful, prespecified data collection might better inform treatment decisions for survivors of cardiac arrest.
“We are left admitting there is much that we simply do not know,” wrote Kristen K. Patton, MD, and Jeanne E. Poole, MD. “As (SCA) survivor rates continue to improve, we will increasingly be faced with the complex decision of whether effective yet imperfect ICD therapy is warranted in a specific person. Given the high stakes of life, neurological disability, and death, our patients deserve critical thinking and more data to guide this crucial decision.”
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.