Blood Test Predicts Heart Attack Risk

High-sensitivity cardiac troponin T (hs-cTnT) is a relatively new biomarker used in the diagnosis of heart attack and is detectable in the blood several hours before older methods of measuring troponins.

Patients presenting to the emergency department with chest pain and an undetectable level of the blood biomarker hs-cTnT, and whose electrocardiography show no sign of restricted blood flow, have a minimal risk of heart attack within 30 days.

Scientists at the Karolinska University Hospital (Stockholm, Sweden) studied 14,636 patients reporting to a Swedish emergency department with chest pain over a two-year period from 2010 to 2012. They evaluated if an undetectable level of less than 5 ng/L of hs-cTnT, and an electrocardiogram (ECG) without signs of ischemia can rule out myocardial infarction in the emergency department. Nearly 9,000 patients with an undetectable level of the biomarker, or less than 5 ng/L, on initial testing, and whose ECGs showed no heart damage from decreased blood flow, were included in the study to examine the primary endpoint of heart attack within 30 days.

The hs-cTnT levels were analyzed using the Elecsys 2010 system (Roche Diagnostics GmbH, Mannheim, Germany). This method has a detection limit of 2 ng/L, a 99th-percentile cutoff point of 14 ng/L, and a coefficient of variation of less than 10% at 13 ng/L. Patients were categorized into three groups according to the first hs-cTnT level: less than 5 ng/L, 5 to 14 ng/L and greater than 14 ng/L.

During the 30 days of follow-up, 39 of the 8,907 patients were diagnosed with heart attack, and 15 of these patients showed no signs of damage on ECG. According to the scientists this means that only one in 594 patients who seek medical attention for chest pain, but have no signs of heart damage on an ECG and undetectable levels of hs-cTnT are actually at immediate risk of heart attack. The average age of patients in the study was 47, and 53% were women.

Nadia Bandstein, MD, the lead author of the investigation, said, “Despite our observations before the study, we were still surprised by the strength of our findings. Using this blood test along with an ECG, we will save about 500 to 1,000 admissions per year in our hospital alone, allowing us to use the beds for sicker patients.” The authors recommend that that further studies need to be done to assess the risk of heart attack among patients with slightly higher levels of hs-cTnT, 5 to14 ng/L. It will also be important to look at the prognosis for patients diagnosed with heart attack based on slight elevations of the biomarker. The study was presented at the American College of Cardiology's 63rd Annual Scientific Session, held March 29–31, 2014, in Washington DC (USA)

Related Links:
Karolinska University Hospital
Roche Diagnostics GmbH