Genetic Test Predicts Effect of Beta Blockers

A study has shown that the effectiveness of beta blockers in improving the survival of congestive heart failure patients can be predicted by genetic testing of the angiotensin converting enzyme (ACE) gene. The study, conducted by researchers at the University of Pittsburgh (PA, USA), was published in the March 27 issue of Circulation.

Previous studies have shown that beta blockers are more effective in some patients than in others. A common variation of the ACE gene, the D allele (deletion allele), is missing a small section of DNA. Patients with this allele have higher levels of the hormone angiotensin II, which raises blood pressure. In patients with heart failure, higher levels of angiotensin II lead to a worsening of symptoms. The current study was designed to determine the effect of genetic variation on survival in patients with heart failure, particularly the effect of genetics on the effectiveness of drug therapy.

The study followed 328 patients with heart failure and a mean age of 56 for 21 months. Of these, some were treated with ACE inhibitors, some with angiotensin receptor blockers, and some with beta blockers. The study classified patients into three groups based on whether they had two copies, one copy, or no copies of the ACE D allele. The one-year survival rate was poorer for patients with two D alleles (75%) than for patients with one D allele (77%) or no D alleles (94%).

"This negative impact of the ACE D allele on survival was only seen in patients not on beta blocker therapy, and was virtually eliminated by therapy with these agents,” said Dennis McNamara, M.D., assistant professor of medicine at University of Pittsburgh School of Medicine and principal investigator in the study. The third of the patients with two copies of the D allele showed the maximum benefit from beta blocker therapy, while the benefits of beta blockers in the remaining patients were not as great. "These findings suggest a potential pharmacogenetic interaction between ACE D and beta blocker therapy in the determination of heart failure survival,” added Dr McNamara.



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