New Test Links Blood Protein to Heart Disease, Diabetes Risk
High levels were also associated with risk of death from all causes
TUESDAY, Dec. 7, 2010 (HealthDay News) -- The presence of a certain biomarker in the blood is associated with structural heart disease and increased risk of death from all causes, a new study suggests.
It goes by the name of cardiac troponin T (cTnT) -- a heart-specific protein that serves as a biomarker for diagnosing heart attack.
In addition, elevated cTnT levels are associated with a number of chronic diseases such as coronary artery disease (CAD), heart failure, and chronic kidney disease, according to background information in the study.
"Recently, a highly sensitive assay (test) for cTnT has been developed that detects levels approximately 10-fold lower than those detectable with the standard assay," wrote Dr. James A. de Lemos, of the University of Texas Southwestern Medical Center in Dallas, and colleagues. "In patients with chronic heart failure and chronic CAD, circulating cTnT is detectable in almost all individuals with the highly sensitive assay, and higher levels correlate strongly with increased cardiovascular mortality."
In this study, the researchers used the highly sensitive test and the standard test to measure cTnT levels in 3,546 people, aged 30 to 65, in Dallas County. The prevalence of detectable cTnT among the participants was 25 percent using the highly sensitive test and 0.7 percent using the standard test.
The participants were then put into five categories based on their cTnT levels, and heart structure and function was measured with an MRI.
Detectable levels of cTnT were much more likely to be found in men than in women (37.1 percent vs. 12.9 percent), in blacks compared to Hispanics or whites, and in people aged 60 to 65 (57.6 percent) than in those aged 40 to 50 (14 percent).
The standard test failed to detect cTnT in two-thirds of participants with the highest cTnT levels. Increasing levels of cTnT were associated with higher rates of high blood pressure, diabetes, heart enlargement, heart failure, coronary artery disease, and cardiovascular disease. The rate of diabetes, for example, increased from 7.7 percent to 41 percent along with rising levels of cTnT; the rate of hypertension jumped from 27.2 percent to 70.9 percent as the biomarker levels went up.
After a median (midpoint) follow-up of 6.4 years, there were 151 deaths among the participants, including 62 cardiovascular disease deaths. Death from all causes increased from 1.9 percent to 28.4 percent for those with higher cTnT levels. After adjusting for a number of factors, the researchers concluded that cTnT levels were associated with all-causes mortality.
"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 researchers wrote.
The researchers noted that further studies are needed to see whether the more sensitive test for cTnT levels could add value to traditional heart health risk factors.
The study appears in the Dec. 8 issue of the Journal of the American Medical Association.
The U.S. National Heart, Lung, and Blood Institute has more about heart and vascular disease.