Heart attack test may cut ER diagnosis time

Doctors may be able to diagnose a heart attack in one hour using a new test approach that could save time, money and crowding in hospital emergency rooms, researchers said.

Using more-sensitive screening technology to detect changes in cardiac troponin, a substance in the blood tested for evidence of heart attack, and inputting the data into an algorithm, doctors were able to determine whether a heart attack had occurred in 77 percent of patients within an hour of arriving at the hospital with chest pain, according to research published in the Archives of Internal Medicine.

About 10 percent of all emergency room consultations are for those with heart attack symptoms, the researchers said. Limitations in older tools used to read troponin can delay heart attack diagnosis for as long as six hours, the authors said.

"There's a bit more work to be done to show, that in a prospective fashion, by employing these algorithms you have good clinical results," Kristin Newby, of the Duke University Medical Center, author of an accompanying editorial, said. "This kind of work sets the stage for that and ultimately helps move things forward."

The more-sensitive blood tests aren't available now in clinical practice in the United States, Newby said. Basel, Switzerland-based Roche Holding AG, a sponsor of the study, donated the blood assay used in the research.

With conventional tests it can take three to four hours before doctors can detect an increase in troponin levels.

The researchers looked at 872 patients who went to the hospital with chest pains. They used 436 patients' troponin levels to develop the algorithm and validated the results in the remaining people.

Heart attack was diagnosed in 17 percent of all the patients. After using the algorithm, 259 people were classified as not having a heart attack, 76 were confirmed as having one and 101 were put in an observational zone within one hour of arriving at the hospital.

They found 30-day survival was almost 100 percent in those ruled out as having a heart attack, 99 percent in those in the observational group and 95 percent in the heart attack group.

"These assays are incredibly sensitive. We're still in some ways looking for how to implement them effectively," she said. "This is a big step forward in understanding how to employ them in what can be a very confusing environment, to tease out heart attacks from many other things."