High levels of two proteins in the bloodstream indicate need for action to avoid heart attack

Researchers working to decode chemical SOS signals sent out by disease-damaged hearts believe they now know better when to aggressively clear clogged arteries and when medical procedures may be unnecessary and even harmful.

The research, led by Uppsala University in Sweden, appears in the Sept. 19 edition of the Journal of the American College of Cardiology.

According to the research, high levels of two proteins in the bloodstream indicate that patients with acute coronary syndromes - chest pain caused by lack of blood to the heart - are at high risk of having potentially fatal heart attacks. Taking aggressive action to treat their blocked arteries will reduce their risk of dying within one year.

On the other hand, patients with low levels of these proteins, also called biomarkers, are not at high risk for deadly heart attacks and may even be harmed by having angioplasty or bypass surgery to treat blocked arteries.

The proteins - troponin-T (TnT) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) - are just two of the biomarkers being studied by physicians and scientists around the world in an effort to improve treatment for a wide range of illnesses.

"Biomarkers are analyzed in blood samples taken from patients when they are admitted to the hospital," said Stefan James, MD, PhD, senior consultant cardiologist and catheterization laboratory director for Uppsala University Academic Hospital's Department of Cardiology. "With a better understanding of these markers, we will be able to assess risk for individual patients more accurately.

"We will also be able to individualize treatment alternatives," said Dr. James, lead author of the new study. "Thereby, we may avoid costly and potentially hazardous treatments for patients at low risk and still provide lifesaving and symptom-relieving medical and surgical treatments for those at high risk."

For the study, researchers conducted a statistical analysis of data collected as part of the Global Utilization of Strategies To open Occluded arteries-IV trial (GUSTO-IV). Records of 2,340 patients who underwent procedures to clear their blocked arteries within the first 30 days of the international trial were included in the analysis. All of these patients were diagnosed with non-ST segment elevation acute coronary syndromes. Non-ST segment elevation refers to how the heart beat appears when displayed in graph form.

Researchers found that if either TnT or NT-proBNP levels were elevated, patients benefited from aggressive treatment to clear their coronary arteries. But if either level was low or non-existent, patients did not benefit. In this group, undergoing invasive medical procedures resulted in a significant increase of death within one year of treatment. All results were independent of other chemical biomarkers in the blood, including C-reactive protein and interleukin-6.