January 15, 2009 - Implantable cardioverter defibrillators (ICDs) may reduce the risk of death by 30 percent in older patients with reduced heart function, according to research reported in Circulation: Cardiovascular Quality and Outcomes.
Paul Chan, M.D., M.Sc., lead author of the study and assistant professor at the Mid-America Heart Institute and the University of Missouri in Kansas City, said that ICDs reduced the risk of dying by 30 percent in patients younger than 65 years old, 65 to 74, and 75 and older.
This primary prevention study recruited 986 consecutive patients with a median age of 67 who had diminished left ventricular function where the heart was functioning at no more than 35 percent of capacity. Patients were treated from March 2001 though June 2005 and followed through March 2007.
Researchers compared outcomes of 500 patients who received ICDs to those who didn't receive the devices. Overall, 238 deaths occurred - 130 (26.7 percent) in the non-ICD group and 108 (21.6 percent) in the ICD group. Of these, 116 were attributed to arrhythmia - 67 (13.7 percent) in the non-ICD group and 49 (9.8 percent) in the ICD group.
"The ICD reduced all-cause mortality by 30 percent compared with patients who didn't receive ICDs," Dr. Chan said. "The use of ICDs in general practice reduced mortality similar to the levels seen in clinical trials. And, the use of ICDs in older patients and patients with comorbidities reduced mortality both in relative and absolute terms."
When researchers studied patients aged 75 or older, they found that the level of survival benefit remained intact. But the benefit diminished when age was combined with multiple disease conditions.
The caveat, Dr. Chan said, was that "cost effectiveness estimates for ICD therapy in this study population depended upon both the degree and the number of comorbidities." He and his colleagues also reported in the paper cost-effectiveness estimates for the use of ICD therapy by age and comorbidity subgroups.
The study was limited because of the relatively few patients in their 80s. "I feel comfortable applying the findings to septuagenarians, but we continue to have limited data on ICD use among octogenarians," Dr. Chan said.
Co-authors are Brahmajee K. Nallamothu, M.D., M.P.H.; John A. Spertus, M.D., M.P.H.; Frederick A. Masoudi, M.D., M.S.P.H; Cheryl Bartone, B.S., M.P.H.; Dean J. Kereiakes, M.D.; and Theodore Chow, M.D. Individual author disclosures can be found on the manuscript.
For more information: www.americanheart.org