New ultra-sensitive blood tests can rapidly detect when heart muscle is dying from a heart attack, even from the moment the patient arrives in the emergency room, according to two studies on Wednesday.

With older tests, it can be hours before telltale levels of the chemical cardiac troponin appear in the blood, delaying diagnosis and treatment. But the new tests work more quickly and more accurately, the studies found.

About 15 million people show up in emergency rooms in the U.S. and Europe each year with symptoms of a heart attack, also known as a myocardial infarction.

Faster test could save time, billions of dollars and many lives by speeding treatment or helping doctors quickly determine if a heart attack is not causing a patient’s symptoms.

“The cost savings associated with this increase in early diagnostic accuracy might be substantial,” Dr. Tobias Reichlin of University Hospital Basel in Switzerland and colleagues wrote in one of the two reports published in the New England Journal of Medicine.

Electrocardiograms, which measure the electrical activity of the heart, and a cardiac Troponin Test, which looks for the release of a protein unique to the heart, are the best measures of a heart attack.

But it can take hours for troponin to get into the blood at levels high enough to be measured.

The new studies, both conducted in Europe, were designed to see if the new generation of troponin-detectors were sensitive enough to be used sooner.

Reichlin’s group looked at 718 patients and found that all four ultrasensitive troponin-detection tests were better than an older Roche assay at picking out the 123 people who had actually suffered a heart attack.

HIGHLY ACCURATE

All four tests correctly spotted a heart attack upon admission in at least 94 percent of the cases, compared to the standard Roche test which was accurate 90 percent of the time.

“These assays can substantially improve the early diagnosis of acute myocardial infarction, particularly in patients with a recent onset of chest pain,” they concluded.

Two of the tests are made by Roche AG, one by Siemens AG and one is made by Abbott. The companies helped pay for the research.

The second study, conducted at three German medical centers, looked at the Siemens test and found comparable results. Siemens was not involved in that test.

But that team, led by Dr. Till Keller of Johannes Gutenberg University in Mainz, cautioned that other studies are needed to see if rapid diagnosis actually translates into a better result for heart attack patients.

The four new tests were Abbott-Architect Troponin I, Roche High-Sensitive Troponin T, Roche Troponin I and Siemens Troponin I Ultra.

SOURCE: New England Journal of Medicine, August 27, 2009.