Simple Scale Could Help Emergency Room Physicians Identify Sickest Heart Attack Patients
ANAHEIM, CA -- Duke University Medical Center cardiologists have developed a simple numerical scale that could help emergency room physicians quickly determine which suspected heart attack patients truly have severe coronary artery disease (CAD) and which don't.
This is important, they say, because one in eight patients who come to the hospital with chest pains are shown by later diagnostic tests to have mild to no blockages in their coronary arteries. These patients don't need expensive tests and don't benefit from the new anti-platelet medications, while those with significant CAD show a clear benefit from such interventions.
After analyzing 16 different characteristics of more than 5,700 patients, the researchers found that the most important predictors of insignificant CAD were younger age, female gender and the lack of a previous heart attack. These and the other 13 characteristics - such as smoking history, cholesterol levels, race and diabetes, as well as ECG findings - are given weighted values depending on individual patients.
"Where the total score occurs along a continuum gives us a good idea of the severity of a patient's coronary artery disease," said cardiologist Dr. Matthew Roe of the Duke Clinical Research Institute.
"Emergency rooms can be busy places, so it would be very helpful to have a non-invasive tool that would allow physicians to quickly and effectively determine which patients need to be sent on for further testing and treatment, and those that can be treated less aggressively and safely discharged," Roe said. He anticipates testing his new model in an emergency room setting in the near future.
Roe prepared the results of the Duke study for presentation Sunday (March 12) at the 49th annual scientific sessions of the American College of Cardiology.
Roe and colleagues analyzed the data of the recently completed PURSUIT (Platelet glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy) trial, which enrolled 10,948 patients in 27 countries. The drug eptifibatide (trade name Integrilin) is a member of a new class of drugs known as glycoprotein IIb/IIIa inhibitors, or so-called "super aspirin," which keep platelets in the blood from clumping together.
Roe and colleagues sifted through the PURSUIT records and identified 5,767 patients who came to the hospital with chest pains and who then received in-hospital angiography, an invasive radiologic procedure that determines to what degree the arteries feeding the heart are clogged.
The researchers found that 88 percent of those patients were found to have coronary arteries that were greater than 50 percent clogged, 6 percent had mild blockage (less than 50 percent) and the other 6 percent had no blockages. Eptifibatide was found to reduce the incidence of subsequent death or heart attack within 30 days for those patients with significant CAD, but had no effect on those with insignificant CAD, according to Roe.
By comparing the different characteristics of those with and without significant CAD, the researchers were able to develop the predictive scale.
"It is important that we have a way to triage patients with significant coronary disease to appropriate therapies, as well as identifying patients who don't need aggressive treatment," Roe said. He added that this method of distinguishing patients was inexpensive, and though his was not an economic study, he said that health care dollars would be saved by reducing the utilization of diagnostic tests, medication costs and hospital lengths of stay.
All the data that go into this model are routinely gathered as soon as a patient arrives, meaning that physicians would not have to do anything extra to complete the model, Roe added.
To test whether or not this approach was predictive in a different set of patients, Roe's team applied the model to another large, multi-center trial known as GUSTO-IIb (Global Use of Strategies To Open occluded coronary arteries in acute coronary syndromes). That trial enrolled 8,011 patients who had similar characteristics as those patients enrolled in the PURSUIT trial.
"When we tested the model against the GUSTO population, most of the 16 factors remained significant, leading us to believe that this could be a very useful tool for emergency room physicians," Roe continued. "Of course, the model needs to be tested further in an emergency room setting, but we feel it has great potential."
Roe does point out that the patients considered to have insignificant CAD by his model still may be at risk for a heart attack at some point in the future, adding that it may have been early in the disease process for these patients or that they had tiny plaques or plaques in smaller vessels not detected by angiography. These patients are usually advised to follow up with their physician or cardiologist.
The PURSUIT trial was funded by COR Therapeutics, San Francisco, the developer of eptifibatide.