Blood Test Measures Risk of Dying from Unknown Heart Disease

Kathleen Blanchard's picture
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A new and sensitive blood test can measure whether a person has heart disease, doesn't know it and is at risk for dying within the next six years. Researchers at UT Southwestern Medical Center say the test can detect levels of an enzyme in 25 percent of people who have no symptoms of heart failure or coronary artery disease.

Blood Test Predicts Risk of Heart Related Death in General Population

The test can measure low levels of a protein in the bloodstream called cardiac troponin T, or T (cTnT) that is a biomarker used to determine whether a person is having a heart attack.

In the current study that used a newly developed sensitive assay to measure troponin T levels, researchers followed 3,546 people, aged 30 to 65, who were part of the Dallas Heart Study that began in 2000. The new findings build on previous research showing that the protein could be detected in one percent of the population to predict the chances of dying from heart disease that included 6100 Dallas County residents.

The study participants were followed an average of 6.4 years and underwent MRI and CT scanning of the heart and other organs. The researchers then tracked causes of death in subjects age 30 to 65 through 2007, finding that low levels of the protein in the bloodstream can predict death from all causes.

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Dr. James de Lemos, associate professor of internal medicine at UT Southwestern and lead author of the study explains, "Prior studies have described associations between increased troponin levels detected with standard assays and future risk for mortality. Here, we report that these associations extend to much lower troponin levels not detected with assays in current clinical use."

The study found that any detectable levels of troponin T raised the chances of dying from heart disease 7 fold within six years.

Levels of cTnT were most often detected in men, compared to women (37.1 percent vs. 12.9 percent), more often in blacks compared to whites or Hispanics, and the 60 to 65 age group (57.6 percent) versus ages 40 to 50 (14 percent).

Dr. de Lemos says the new and more sensitive test may replace the less sensitive cardiac troponin test used by emergency room physicians to detect heart attack for individuals with chest pain. He adds however, "With the new highly sensitive assays, it's going to be much more difficult to determine if elevated levels of troponin T are due to a heart attack or rather another chronic form of disease."

The new, more sensitive troponin test can detect circulating cTnT levels in almost anyone with coronary artery disease or heart failure, before symptoms develop. The test can be used in younger populations to prevent death and disability from unknown, asymptomatic heart disease. Previous studies looked at the usefulness of the measuring the protein level in adults over age 65 in research led by Dr. Christopher deFilippi of the University of Maryland School of Medicine.

JAMA 2010;304[22]:2503-2512.

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