The researchers created genetically altered mice and found those with leucine seemed to have a kind of natural beta blocker that reduced the impact of the adrenaline rush that normally prompts a stressed heart to work harder.
The researchers then tracked 375 black heart failure patients, some of whom were being treated with beta blockers by their physicians.
Among those with glutamine, the beta blockers were beneficial: At the end of an observation period that ran as long as eight years, 50 percent of those taking beta blockers were still alive, while only 20 percent of those not on beta blockers had survived, Liggett said.
But volunteers with leucine had the same 50 percent survival rates whether they took a beta blocker or not.
The study, funded by the National Heart, Lung, and Blood Institute, was conducted with help from researchers at the Washington University School of Medicine, the University of Cincinnati College of Medicine and the University of Michigan.
Liggett, director of Maryland's cardiopulmonary genomics program, hopes genetic tests will soon be available to help doctors determine which patients should take beta blockers. He eventually wants to develop a kind of scorecard, made up of genetic test results, that doctors could use when deciding whether beta blockers and other medications are appropriate.
"Our goal here is not to take away the physicians' judgment, but to give them some handles to work with, to know when to use a specific drug," he said.
dennis.obrien@baltsun.com
