(HealthDay News) — Implantable cardioverter-defibrillators (ICDs) may not benefit all patients to the same degree, as their effectiveness seems to diminish somewhat with the advancing age of the patient, according to a review published online February 10 in Circulation: Cardiovascular Quality Outcomes.

Paul Hess, MD, a clinical fellow in the department of cardiology at the Duke University Medical Center in Durham, NC, and colleagues noted that >40% of ICD patients are ≥70 years of age at the time they undergo surgery. More than 10% are ≥80 years of age. By contrast, almost 90% of the 3,500 participants enrolled in the five studies under review were <75 years of age. And while patient age ranged from <55 to >75, the overall average age of the patient pool was just 62. Roughly half the participants received an ICD because they had been deemed at high risk for sudden cardiac death. The other half did not have the device implanted. Each patient was tracked for an average of 2.6 years.

During that time, more than a fifth of those who received an ICD died, compared to more than a quarter of those who did not get an ICD. Overall, the researchers found that those who got ICDs were less likely to die than those who did not, seemingly regardless of age. However, the researchers also said that ICDs seem to offer poorer survival rates among older patients, perhaps because older patients tend to have additional health complications alongside heart disease. And the researchers warned that given the small pool of older patients, it could not be ruled out that ICDs may actually provide little or no survival benefit among patients >70 years of age.

“We really need more studies to look at this question more carefully so we can shed some light on how ICDs work among older patients,” Hess told HealthDay. “Meanwhile, I would say that it’s possible that chronological age may not be the only important measure to consider, that how healthy a person is and how large their burden of additional disease – what we call ‘biologic age’ – may be really important to take into account when considering whether an ICD is right for someone in their 70s or older.”

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