In this post I link to and excerpt from Emergency Medicine Cases‘ JJ 15 Cardiac Stress Testing After Negative ED Workup for MI [Link is to the podcast and show notes] of April, 2019, by Drs Helman, Morganstern and Spiegel . Here is the introduction to this podcast and show notes:
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?
Here are excerpts:
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.
*Non–ST-Elevation Acute Coronary Syndromes (Jun 2018): Critical Issues in the Evaluation and Management of Emergency Department Patients with Suspected Non–ST-Elevation Acute Coronary Syndromes [PubMed Abstract] [Full Text HTML] [Full Text PDF]. Ann Emerg Med. 2018 Nov;72(5):e65-e106. From the American College of Emergency Physicians.
See the article above for full details on ACEP answers to three critical questions:
- In adult patients without evidence of ST-elevation acute coronary syndrome, can initial risk stratification be used to predict a low rate of 30-day major adverse cardiac events?
- Level B Recommendations
In adult patients without evidence of ST-elevation acute coronary syndrome, the History, ECG, Age, Risk factors, Troponin (HEART)* score can be used as a clinical prediction instrument for risk stratification. A low score (≤3) predicts a 30-day major adverse cardiac event miss rate within a range of 0% to 2%. * HEART Score for Major Cardiac Events: Predicts 6-week risk of major adverse cardiac event. From MDCalc.
- Level C Recommendations
In adult patients without evidence of ST-elevation acute coronary syndrome, other risk-stratification tools, such as Thrombolysis in Myocardial Infarction (TIMI), can be used to predict a rate of 30-day major adverse cardiac event.
- In adult patients with suspected acute non–ST-elevation acute coronary syndromes, can troponin testing within 3 hours of emergency department presentation be used to predict a low rate of 30-day major adverse cardiac events?
- Level C Recommendations
- In adult patients with suspected acute non–ST-elevation acute coronary syndrome, conventional troponin testing at 0 and 3 hours among low-risk acute coronary syndrome patients (defined by HEART score 0 to 3) can predict an acceptable low rate of 30-day major adverse cardiac events.
- A single high-sensitivity troponin result below the level of detection on arrival to the emergency department, or negative serial high-sensitivity troponin result at 0 and 2 hours is predictive of a low rate of major adverse cardiac events.
- In adult patients with suspected acute non–ST-elevation acute coronary syndrome who are determined to be low risk based on validated accelerated diagnostic pathways that include a nonischemic ECG result and negative serial high-sensitivity troponin testing results both at presentation and at 2 hours can predict a low rate of 30-day major adverse cardiac events allowing for an accelerated discharge pathway from the emergency department.