ED Testing Strategy: No Effect on Risk of Future MI in Chest Pain Patients

October 9th, 2016

HERSHEY, PA – To test or not to test – that often is the question when patients present to the emergency department with chest pain.

A new study provides some information helpful in making that decision: Chest pain patients seen in the ED who did not have a heart attack appear to be at low risk of subsequently experiencing a heart attack during short- and longer-term follow-up. Furthermore, according to the recent report in JAMA Internal Medicine, the risk was not affected by the initial diagnostic testing strategy.

Background information in the article notes that about 6 million patients are seen in EDs annually for chest pain or other symptoms suggestive of myocardial ischemia, explaining that patients without objective evidence of ischemia have been shown to have low risk for a major cardiovascular event. In fact, most patients do not even have a cardiac cause for their symptoms.

The study, led by researchers from the Penn State Milton S. Hershey Medical Center, compared chest pain evaluation to outcomes for ED patients using private health insurance claims data in 2011.

Patients with chest pain diagnoses were classified into 1 of 5 testing strategies:

• no noninvasive testing,
• exercise electrocardiography,
• stress echocardiography,
• myocardial perfusion scintigraphy (MPS), or
• CCTA, CT imaging.

The researchers then measured the proportion of patients in each group who received cardiac catheterization, a coronary revascularization procedure or future noninvasive test, as well as those hospitalized for acute myocardial infarction (MI).

In 2011, the 693,212 emergency visits with a chest pain diagnosis accounted for 9.2% of all ED encounters, according to the study. The final study analysis included 421,774 patients, of which 293,788 did not receive an initial noninvasive test while 127,986 underwent testing, most frequently MPS.

Overall, only 0.11% of patients were hospitalized with heart attack at the seven-day follow-up and 0.33% at the 190-day follow-up, according to the results.

“Patients who did not undergo initial noninvasive testing were no more likely to experience an MI than were those who did receive testing,” according to the authors. “Compared with no testing, exercise electrocardiography, myocardial perfusion scintigraphy, and coronary computed tomography angiography were associated with significantly higher odds of cardiac catheterization and revascularization procedures without a concomitant improvement in the odds of experiencing an MI.”

"More studies need to be conducted to clarify the best testing strategy for low-risk patients being evaluated for chest pain in the ED. … Given today's concerns regarding health care cost growth, especially the portion attributable to noninvasive cardiac imaging, and patient safety issues related to radiation exposure as well as over-diagnosis, performing such a study should be a priority," the study concludes.

In a related editor's note, JAMA Internal Medicine Editor Rita F. Redberg, MD, MSc, writes: "These findings suggest that the current practice of performing a stress test on low-risk patients in the ED is unnecessary and prolongs the length of stay in EDs as well as increases unnecessary medical imaging, with significant associated radiation risk for tests that include nuclear imaging. It is time to change our guidelines and practice for treatment of chest pain in low-risk patients. Such patients should be given a close follow-up appointment with a primary care physician who can determine, based on the patient's condition, whether further evaluation is necessary."