In a large primary-prevention population with moderately symptomatic heart failure, single-lead implantable cardioverter–defibrillator (ICD) therapy was not associated with any detectable adverse quality-of-life effects during 30 months of follow-up, according to a study in the Sept. 4 issue of the New England Journal of Medicine.
According to Daniel B. Mark, MD, from the Duke University Medical Center in Durham, N.C., and colleagues, ICD therapy significantly prolongs life in patients at increased risk for sudden death from depressed left ventricular function. The researchers undertook the study to determine whether the increased longevity is accompanied by deterioration in the quality of life.
In a randomized trial, the investigators compared ICD therapy or amiodarone with medical therapy alone in 2,521 patients who had stable heart failure with depressed left ventricular function. They prospectively measured quality of life at baseline and at months three, 12 and 30.
The Duke Activity Status Index, which measures cardiac physical functioning, and the Medical Outcomes Study 36-Item Short-Form Mental Health Inventory 5, which measures psychological well-being, were pre-specified primary outcomes, according to the authors.
Mark and colleagues found that psychological well-being in the ICD group, as compared with medical therapy alone, was significantly improved at three months and at 12 months, but not at 30 months. No clinically or statistically significant differences in physical functioning among the study groups were observed.
The researchers found that additional quality-of-life measures were improved in the ICD group at three months, 12 months, or both, but there was no significant difference at 30 months. ICD shocks in the month preceding a scheduled assessment were associated with a decreased quality of life in multiple domains.
The use of amiodarone had no significant effects on the primary quality-of-life outcomes, according to the investigators.
However, in a sub-group analysis, the researchers found that patients in the ICD group, who received five or more shocks, did not have improvement in these quality-of-life scales, as compared with patients who received fewer than five shocks. However, the quality-of-life scores for patients in the ICD group who received one to four shocks during follow-up did not differ significantly from those for patients who received no shocks.
Mark and colleagues noted that their evaluation of the effects of ICD shocks on subsequent quality of life was limited by the lack of quality-of-life data linked to the delivery of ICD shocks, and by the relatively small number of patients with a quality-of-life assessment shortly after a shock episode. They said that they did not have enough patients with multiple shock episodes during a 24-hour period to determine the effects of that phenomenon on subsequent quality of life.
Based on their findings, the authors concluded that the random assignment to the ICD group was not associated with adverse effects on health-related quality of life during the first 30 months of follow-up.