More accurate assay speeds heart attack diagnosis

Doctors may soon be able to more readily determine whether patients are having a heart attack when they arrive in the emergency room with acute chest pain. Researchers from the University Heart Center Hamburg in Germany have developed a more sensitive test for measuring troponin I, an enzyme that is released from damaged cardiac muscle cells during the acute stages of a heart attack (myocardial infarction, or MI), and is therefore elevated in the blood early on during MI.

Currently, doctors use a less sensitive troponin I assay to diagnose MI. However, as the researchers report in the Journal of the American Medical Association, the newer assay allows for more reliable diagnosis of patients whose troponin I levels would otherwise not be detectable. The level of detection for the newer assay is nearly three times as sensitive as the older assay.

In the study of over 1,800 patients with chest pain indicating possible acute coronary syndrome, clinicians combined information from hospital admission with the relative change in troponin I levels in the first three hours, demonstrating that they were able to correctly diagnose MI 96 percent of the time. However, while the more sensitive assay could well lead to an improved identification of MI, the researchers noted that future studies should examine whether this method actually improves patient care and outcomes.

The difference between the new, highly sensitive troponin I assay and the older method is not large, notes ACSH s Dr. Gilbert Ross. However, further, more complex studies should assess whether the enhanced sensitivity will lead to more rapid diagnosis of MI in the emergency room. And in the face of an acute coronary blockage, he says, every minute saved means more heart muscle preserved.