Michael Kontos, M.D.Institution: Virginia Commonwealth University
Protein test sets new standard for heart attack detection
A blood test has been developed to help diagnose heart attacks in people with chest pain. The test detects elevated protein levels associated with dying heart cells.
The American College of Cardiology and the European Society of Cardiology have recommended that any elevation of a protein called troponin should be considered a heart attack. However, different tests evaluate the levels of troponin and different elevation cutoff points are being used.
The challenge, said Michael Kontos, M.D., assistant professor of internal medicine and cardiology at Virginia Commonwealth University in Richmond, is to pinpoint which assay best measures the level of troponin and for the medical community to agree upon what cutoff point is considered a heart attack.
“The troponin test has significant predictive value, suggesting that the number of mild heart attacks in such patients is far greater than we have been able to recognize in the past,” Kontos said. “Evaluating patients with symptoms suggestive of a heart attack can be difficult when an electrocardiogram is inconclusive. Over a four-year period, we have found that troponin at lower levels is more sensitive for diagnosis of heart attack.”
Traditionally, doctors have looked for evidence of a heart attack by looking at levels of an enzyme, called creatine kinase (CK-MB), released by heart attack and other damaged tissues. In Dr. Kontos’ study, the incidence of heart attack when CK-MB was used as the marker was 8.3 percent. When troponin was used as the marker, the incidence increased a relative 160 percent.
Normally the level of troponin I in the blood is very low, and is usually undetectable. It increases substantially within several hours (on average four to six hours) of heart muscle damage. It peaks at 10 to 24 hours and can be detected for a week or more after.
“An elevated troponin test identifies people at risk for both early and later heart problems”, Kontos said.
Dr. Kontos was supported early in his career with an American Heart Association Mid-Atlantic Affiliate Fellowship award.