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Advanced age, comorbidities may weaken ICD survival benefit
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The survival benefit of implantable cardioverter defibrillator therapy appears to diminish with increasing patient age and may be associated with an attendant increase in comorbidity burden, according to recent findings.
Researchers pooled patient-level data from 3,530 participants in the following five major ICD trials: MADIT-1, MUSTT, MADIT-II, DEFINITE and the SCD-HeFT. The cohort included 1,836 ICD recipients and 1,694 nonrecipients. The median age at enrollment was 62 years, with 11% patients aged at least 75 years.
Among the incorporated trials, the individual patient inclusion criteria included NYHA class III HF, left ventricular ejection fraction less than 35%, and available information on key covariates. The primary endpoint was all-cause mortality, and the secondary endpoint was all-cause rehospitalization, with a median follow-up of 2.6 years.
Death occurred in 21.3% of ICD recipients and 30.6% of nonrecipients. A survival benefit from ICD implantation was observed across all age groups, after adjustment for factors such as demographics, comorbidities and laboratory values. Hospitalization occurred in 71.4% of ICD recipients and 60.2% of nonrecipients. Compared with nonrecipients, the HR for mortality was 0.48 (95% posterior credible interval, 0.33-0.69) for those younger than 55 years; 0.69 (95% posterior credible interval, 0.53-0.9) for patients aged 55 to 64 years; 0.67 (95% posterior credible interval, 0.53-0.85) for those aged 65 to 74 years; and 0.54 (95% posterior credible interval, 0.37-0.78) for those aged 75 years or older. However, the researchers acknowledged a small sample size for patients aged at least 75 years, and that this may have influenced efficacy estimates and the observed survival benefit.
Adjusted Bayesian-Weibull modeling point estimates indicated that ICD efficacy persists with advancing age, but the effect is diminished. The researchers observed evidence of a potential interaction between age and ICD treatment influencing survival (two-sided posterior tail probability of no interaction < .01). No evidence of a relationship was observed between age and ICD treatment and rehospitalization (two-sided posterior tail probability of no interaction = 0.44).
According to the researchers, the observed decrement in ICD survival benefit may be related to an accompanying increase in comorbid disease burden among older patients.
“The current analysis suggests age per se is not a strict contraindication to placement of an ICD, but rather patients and physicians should take into account a number of other factors, such as patient preference, procedural risk, and comorbidity burden,” the researchers wrote. – by Jennifer Byrne
Disclosure: Hess and another researcher report receiving consulting fees/honoraria from Sanofi-Aventis.
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