THE EFFECTIVENESS OF BETA BLOCKERS — Researchers at the University of Maryland School of Medicine say they have solved a mystery that has intrigued cardiologists for years: why one of the most commonly prescribed heart medications doesn't always work.
The effectiveness of beta blockers - a class of drugs given to many of the estimated 5 million patients with chronic heart failure - depends on the genetic makeup of receptors in the heart, said Dr. Stephen B. Liggett, head of the school's cardiopulmonary genomics program and lead author of the beta blockers study.
The findings, published today in Proceedings of the National Academy of Sciences, could help determine the course of treatment for those with chronic heart failure, sometimes called congestive heart failure. A genetic test could be approved by the Food and Drug Administration in the next year or two, the researchers say.
"I think this is really exciting news for people who treat heart patients, both cardiologists and internists," said Dr. Roger S. Blumenthal, a cardiologist who is director of the Johns Hopkins Ciccarone Preventive Cardiology Center and was not involved in the study.
The study focused on patients diagnosed with heart failure, and the researchers say they are unsure if the benefits would apply to patients who take beta blockers to lower blood pressure or prevent heart attacks. Separate studies would have to be conducted to determine that, they say.
"This may be something that's particular to heart failure patients," said Dr. Michael Bristow, a cardiologist at the University of Colorado School of Medicine and a co-author.
Bristow and other experts say the findings also represent a step toward a goal that has been the subject of medical research for years - tailoring therapies and medications based on individual genetic differences. Promising results for genetically tailored therapies have also been discovered by researchers probing childhood leukemia, asthma, breast cancer and anti-coagulant drugs, Liggett said.
Heart failure usually develops when the heart is unable to pump enough blood to supply the body. The heart tries to compensate by growing larger and pumping faster.
Someone is predisposed to heart failure if they have had a heart attack or have high blood pressure, abnormal heart valves or diabetes. Because the changes occur gradually, symptoms are often missed until the heart can't keep up with the body's requirements and a person begins to feel fatigued and have trouble breathing.
