JJ 15 Cardiac Stress Testing After Negative ED Workup for MI

Robert Bruce, an American Cardiologist, is considered the founder of exercise cardiology. He created the Bruce Protocol in the early 1960s. Sixty years later, cardiac stress testing has been pretty much the standard for screening low risk chest pain patients for coronary disease after a visit to the ED. It makes intuitive sense. If someone has narrowing of their coronaries and you get their heart rate up with a bit of exercise, you’re increasing demand; and if you see some ST changes or the person develops angina, well - they probably have a coronary lesion that needs to be fixed or medicated to prevent them from having an MI - right? Well, it turns out that this 60 year long belief, that has led hundreds of thousands of people to angiograms, cardiac stents and CABGs, may be wrong. In this Journal Jam podcast we do a deep dive into the hugely complex literature of cardiac stress testing and see whether or not stress testing portends any benefit for patients who we assess in the ED for chest pain. The problem is - if stress testing doesn’t benefit our patients and isn’t a good screening test for preventing MIs, then what do we do with our low risk chest pain patients we see in the ED?   Cite this podcast as: Helman, A. Morgenstern, J., Spiegel R. Cardiac Stress Testing After Negative Workup for MI. Emergency Medicine Cases. April, 2019. https://emergencymedicinecases.com/cardiac-stress-testing/. Accessed [date]   Take Home Points on Cardiac Stress Testing After Negative ED Workup for MI The miss rate for MI after an ED visit with nondiagnostic ECG and negative cardiac biomarkers is about 0.2%, not 2%. The patients who are sent for stress tests after a negative ED workup are extremely low risk to begin with. Stress tests have a high false positive rate (as high as 80%) leading to unnecessary angiograms, cardiac stents and CABG. They are poor at identifying coronary artery disease and stress test studies in low risk chest pain patients suffer from inclusion bias. The sensitivity for 30 day MI and death is close to 0% in patients with a negative ED workup. Stress echo and nuclear stress testing have slightly better accuracy than treadmill exercise stress testing in identifying coronary artery disease, but have never been shown to improve patient oriented outcomes after a negative workup in the ED. Except in STEMI and unstable NSTEMI, cardiac stents do not have convincing evidence of benefit, and may be harmful. Patients with negative ED workups but positive stress tests usually go on to have angiograms and some get stents or CABG. While invasive management in patients with stable NSTEMI and unstable angina may decrease symptoms of angina and rehospitalization, they do not improve mortality rates, and may increase bleeding rates by a small but significant amount. The 2018 ACEP clinical policy paper on suspected non ST elevation ACS asks: “In adult patients with suspected NSTEMI ACS in whom acute MI has been excluded, does further diagnostic testing for ACS prior to discharge reduce 30-day MACE?” Level B recommendation: “Do not routinely use further diagnostic testing prior to discharge in low risk patients in whom acute MI has been ruled out to reduce 30-day MACE.” Level C recommendation:  “Arrange follow-up in 1 to 2 weeks for low-risk patients in whom MI has been ruled out. If no follow-up is available, consider further testing or observation prior to discharge." They argue that limiting complex, expensive, and time-consuming testing can reduce patient cost, ED and hospital length of stay, and patient anxiety caused by unnecessary stress testing and potentially false-positive results, once adequate risk stratification and cardiac rule-out have occurred. The American Heart Association guidelines recommends to work within your hospital system to establish an agreed-on approach to minimize medicolegal risk.