New 'Heart Attack' Test Approved

Is it severe indigestion? A hiatal hernia? Pneumonia? Gallstones? Or a heart attack?

The Food and Drug Administration (FDA) has approved a new test that will help emergency room doctors determine if a patient with chest pain is indeed having a heart attack or is suffering from some other ailment whose symptoms mirror those of a heart attack.

The test is the first new blood test to help evaluate heart attacks since 1994.

The Albumin Cobalt Binding (ACB) test measures how much cobalt is bound to the blood protein albumin. Changes in the binding properties of albumin occur during ischemia, a condition in which blood flow and consequently oxygen is restricted to a part of the body.

"This test will significantly increase the ability of doctors to rule out a heart attack," says Sharon Snider, a spokeswoman for the FDA. She stresses, however, that this is not a stand-alone test.

"It must be used together with an electrocardiogram (ECG) and a blood test for troponin. A normal ACB test with a normal ECG and a normal troponin gives doctors increased confidence that patients can go home because they did not have a heart attack."

Serum albumin is a protein in the blood. As albumin circulates in the blood, it comes in contact with ischemic heart tissue, and some of it is converted to ischemia-modified albumin (IMA). Ischemic patients have proportionately more IMA than non-ischemic patients.

In the ACB test, developed by Ichemia Technology, Inc., a cobalt solution is added to the serum because cobalt binds to normal albumin but not IMA. A chemical analyzer reads the results. If there is more free, or unbound, cobalt, it indicates the presence of abnormal albumin. Several other illnesses also cause similar changes in the binding properties of albumin.

According to Snider, an estimated 3 million to 5 million Americans enter emergency rooms each year with symptoms of a heart attack, but only about 22 percent actually are having a heart attack.

"The rest have a variety of other ailments, such as severe indigestion, hiatal hernia, pneumonia, gallstones and hepatitis," she says.

The FDA approved the ACB test following a study conducted by the test's manufacturer on more than 200 patients who were at significant risk for a heart attack and had severe chest pain. Sixty-three percent of those patients had heart attacks, and the ACB test correctly identified most of the patients who were not having a heart attack.

Snider says, "The study showed that when the ACB test was used together with an ECG and a troponin test, physicians were 70 percent accurate in ruling out heart attack. With the ECG and troponin test alone, physicians were only 50 percent accurate in ruling out a heart attack."

Source:

U.S. Food and Drug Administration

This article was reviewed and updated June 2007.