Old Age Alone Should Not Rule Out ICDs: Pooled Analysis

Marlene Busko

February 13, 2015

DURHAM, NC — In a pooled analysis of five major clinical trials that randomized patients to receive implantable cardioverter defibrillators (ICDs) or usual care for primary prevention, ICD patients of all ages had improved survival[1]. The survival benefit did decline with increasing age, likely due to greater comorbidities with older age, but also because fewer patients age 75 and older were enrolled in these trials, according to Dr Paul L Hess (Duke Clinical Research Institute, Durham, NC) and colleagues.

The study, which was published February 10, 2015 in Circulation: Cardiovascular Quality and Outcomes, also showed that age did not have any effect on rehospitalization after ICD implantation.

"Even when we maximize the yield of the data we have by pooling the data in all the clinical trials, we still have some uncertainty, particularly above the age of 75 years," Hess told heartwire . "So in this setting of uncertainty, we still recommend that patients and physicians have a clear discussion regarding the risks and benefits and alternatives, as we would recommend in all cases, but we can't make definitive statements regarding folks" age 75 or older.

The available data "suggest that age, per se, is not a strict contraindication to ICD placement, but rather, other factors should be considered, such as patient preference, procedural risk, and comorbidity burden," he added.

According to Hess, "looking to the future, [since] folks who are receiving the ICD won't necessarily have the same characteristics in clinical practice as they did in clinical trials, it certainly would be helpful to have further evidence, ideally randomized, regarding the efficacy of ICDs in older patients."

Elderly Patients Underrepresented in Clinical Trials

More than 40% of new ICDs are placed in patients age 70 and older and more than 10% are placed in patients age 80 and older, but questions remain about the efficacy of these devices in very elderly patients who were underrepresented in the clinical trials that evaluated these devices, the authors write.

To study the issue in a much larger cohort, they pooled data from five major ICD trials that had their main results published from 1996 to 2005: the Multicenter Automatic Defibrillator Implantation Trial I (MADIT-I), the Multicenter Unsustained Tachycardia Trial (MUSTT), the Multicenter Automatic Defibrillator Implantation Trial II (MADIT-II), the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation Trial (DEFINITE), and the Sudden Cardiac Death in Heart Failure Trial (SCD-HeFT).

They grouped the patients into four age categories: <55 (1010 patients), 55 to 64 (1055 patients), 65 to 74 (1075 patients), and 75 and older (390 patients).

Older patients were more likely to be white and have advanced heart-failure symptoms, atrial fibrillation, hypertension, peripheral vascular disease, and previous PCI or CABG, and they were less likely to be taking a beta-blocker or an ACE inhibitor.

During a median follow-up of 2.6 years, 21.3% of the ICD recipients and 30.6% of the patients who received usual care died. In all age groups, ICD recipients were less likely to die than patients who received usual care.

Death During Follow-up

Baseline age (y) Usual Care ICD
Patients, n Deaths, n (%) Patients, n Deaths, (%)
<55 483 84 (17.4) 527 43 (8.2)
55–64 527 139 (26.4) 528 97 (18.4)
65–74 520 174 (33.5) 555 127 (22.9)
>75 164 66 (40.2) 226 56 (24.8)

Likelihood of Death, ICD Implant vs Usual Care*

Baseline age (years) Hazard ratio (95% posterior credible interval)
<55 0.48 (0.33–0.69)
55–64 0.69 (0.53–0.85)
65–74 0.67 (0.53–0.85)
>75 0.54 (0.37–0.78)
*Unadjusted analysis

The survival benefit with ICD implantation was comparable among men and women younger than 55, but older women had less benefit than older men.

After adjusting for factors other than age that were associated with an increased risk of death, the researchers found that there was increasing uncertainty in the risk of death in older patients, so that the absence of a survival benefit could not be ruled out above age 70.

Age did not influence the rate of hospital readmissions after ICD placement. This "noteworthy" finding contrasts with a previous trial in a real-world setting, and again, deserves further study, according to the authors.

The study was funded by the Agency for Healthcare Research and Quality and an NIH training grant. Hess received consulting fees/honoraria from Sanofi. Disclosures for the coauthors are listed in the article.

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