Cardiac device may be less effective in Blacks
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Implantable cardioverter defibrillators (ICDs) significantly reduce the risk of death in white heart patients, but not in black patients, according to a second look at results from the Multicenter Automatic Defibrillator Implantation Trial (MADIT-II).
This was a surprise finding, Dr. Arthur J. Moss of the University of Rochester Medical Center, New York, told Reuters Health. “We do not have a good reason for the lack of benefit of the ICD in black patients,” he said.
ICDs avert potentially fatal heart rhythms by detecting and correcting early disturbances with a shock. It is known that the ICD reduces death and improves survival in cardiac patients with advanced heart disease. This was shown in the large MADIT-II clinical trial that was reported in The New England Journal of Medicine in 2002.
However, in the secondary analysis of MADIT-II, Moss’s team found that ICD therapy was associated with reduced “hazard ratios” for total mortality, cardiac death, and sudden cardiac in whites, but not in blacks.
The secondary analysis involved 1,073 white and 102 black patients with advanced heart disease. “The lack of ICD therapy efficacy in blacks,” the authors suggest, “may reflect a chance phenomenon in view of the relatively small number of black subjects in MADIT-II…and the limited power to detect ICD therapy benefit in this subgroup.”
They also point out that there were no excess complication rates in black patients compared with white patients to suggest technical or procedural reasons for the racial differences in ICD efficacy.
Blacks in the study had higher body mass indexes than whites, and the researchers suggest it is possible that this could have contributed to reduced ICD therapy efficacy.
SOURCE: American Journal of Cardiology, November 15, 2006.
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