Dec. 7, 2010 -- A newer, more sensitive version of a blood test used to help diagnose heart attacks may have a much wider application as a screening tool for early heart damage, new research suggests.
The test looks for a protein released by injured heart muscle cells called troponin T, and it is typically ordered when patients come to the emergency room with chest painto help doctors discriminate heart attacks from heartburn and other copycat complaints.
But years before such a serious event occurs, troponin T may be present at much lower levels than are seen after heart attacks, a quiet sign of a heart under stress.
And two studies published on Wednesday in the Journal of the American Medical Association, which screened thousands of adults with the so-called highly sensitive cardiac troponin T test, found 1 in 4 between the ages of 30 and 65, and in 2 out of 3 who were over age 65, had measurable levels of the protein.
The studies also found that people with detectable troponin T had significantly greater risks of developing heart failure or dying, compared to those in whom the protein couldn’t be found.
“It’s a pretty remarkable association,” says James A. de Lemos, MD, a cardiologist at the University of Texas Southwestern Medical Center in Dallas who led one of the studies. “It’s way more powerful than CRP [C-reactive protein] or more powerful than other tests that we’ve looked at for sure.”
The new test, which is used in Europe but is not yet available in the United States, can measure troponin T at levels 10 times lower than labs can currently detect, and some experts think it may one day help doctors catch ailing hearts years before symptoms appear.
“That’s the promise of this,” says Robb D. Kociol, MD, a cardiology fellow at Duke University Medical Center in Durham, N.C., who was not involved in the study. “If we can find the damage before it becomes advanced, perhaps we can prevent overt heart failure.”
But other experts caution that more research is needed before the test becomes widely used, largely because there’s very little information to help doctors and patients know what to do with their results.
“We don’t know, for example, if a patient at higher risk for heart failure as identified by troponin testing may benefit from additional medications or a certain kind of clinical workup,” says Willibald Hochholzer, MD, of Brigham and Women’s Hospital in Boston, who was not involved in the study. “There is still much to be learned.”
Many Middle-aged Adults Test Positive for a Marker of Heart Damage
For the first study, researchers performed so-called highly sensitive troponin T tests on blood samples taken from some 3,500 people between the ages of 30 and 65 who were enrolled in the Dallas Heart Study. Participants were then followed for an average of about six-and-a-half years. During that time there were 151 deaths, and 62 of those were caused by heart disease.