WHAT IS PEER TO PEER?
Med-IQ's new complimentary, certified continuing medical education (CME) activity,
Peer to Peer: A New Model for Improving Guideline- and Evidence-Based ACS Care, is connecting healthcare professionals from across the country. This exciting, first-of-its-kind CME series provides participants with access to acute coronary syndrome (ACS) faculty experts during personalized sessions focusing on improving ACS patient care in their practices. This real-time exchange of ideas has helped address some of the major challenges that clinical practices face in managing ACS cases.

WHAT ARE E-BRIEFS?
Each month, Med-IQ will be publishing a short e-brief to highlight real-world questions, opportunities for improvement, and front-line perspectives gained from these ACS Peer to Peer teleconferences. Below, you'll find the second of these e-briefs; in this installment, our expert faculty answer some questions about early risk stratification posed by participants in our peer-to-peer teleconferences.

The quick and accurate early risk stratification of patients with unstable angina (UA)/non-ST-segment elevation myocardial infarction (NSTEMI) is essential to the initiation of appropriate treatment interventions. Despite the existence of ACC/AHA guideline recommendations on risk stratification in the emergency department (ED), the reality is that risk stratification is an inexact science. Many patients have nondiagnostic characteristics that are difficult to interpret.

Interpreting Borderline Troponin Levels
Question: How do I interpret a troponin level that is only slightly elevated—say 0.1 ng/mL—in patients who have no other high-risk features?

Answer: How you interpret a borderline troponin level depends strongly on the patient's history and symptoms. If the patient has symptoms highly indicative of acute coronary syndromes (ACS)—such as prolonged, substernal pain, diaphoresis, and nausea—then that patient is likely to be a high-risk patient. On the other hand, troponin levels can be somewhat elevated in patients who do not have NSTEMI but who have other conditions, such as renal failure, sepsis, and congestive heart failure (CHF). If symptoms don't point to ACS, then you can take a more conservative approach and re-test troponin levels 6 hours after presentation. If the levels are rising, however, it is a strong indication that the patient has ACS.

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Choosing Appropriate Stress Tests
Question: Are there intermediate-risk (TIMI risk score 2 to 3) UA patients in whom stress testing isn't safe? Our facility uses both exercise and pharmacologic stress testing, with nuclear imaging stress test technology.

Answer: Clear guidelines on this topic don't exist; as such, deciding which intermediate-risk patients are safe to stress test depends on several factors, including the intensity of the stress test you plan to use, patient history (especially instability), and comorbidities. Patients with positive biomarkers and a good clinical history for NSTEMI, or those with TIMI risk scores of 2 to 3 who have had a prior infarct or who have diabetes, should probably not undergo stress testing.

ACC/AHA guidelines indicate that prior to stress testing, patients should undergo a period of observation and have two sets of negative cardiac biomarkers 6 hours apart before the test. This would mean that NSTEMI patients should not undergo early testing. There are studies, however, such as TACTICS-TIMI 18 (Treat Angina With Aggrastat and Determine Cost of Therapy With an Invasive or Conservative Strategy), that did perform stress testing 48 hours post medical management for NSTEMI and found it to be safe.¹ Pharmacologic stress testing with imaging can be used when there are physical limitations to exercise stress testing, such as severe peripheral vascular disease, severe chronic obstructive pulmonary disease, musculoskeletal limitations, or general debility.² However, this is a "full" level of stress for the heart and cannot be a "low level" test, so it would not be good for an unstable patient. If you are uncertain about the safety of a stress test, it's best to have the patient evaluated by a cardiologist beforehand.

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Assessing Cocaine Users
Question: How do I correctly risk stratify and manage cocaine users with ACS-like symptoms?

Answer: Young (otherwise) healthy cocaine users under the age of 25 who arrive at the ED with chest pain are likely to have coronary spasm. They can be managed with observation, two sets of biomarkers, and, if results are normal, can then be discharged. Cocaine users in their late 20s and older are more likely to have coronary disease, especially if they are long-term cocaine users. These patients are usually intermediate-risk patients. In addition to observation and two sets of biomarkers, they should undergo stress testing before being discharged.

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Discharging Low-Risk Patients
Question: What about low-risk patients? Is it appropriate to just send them home after evaluating them and determining that they are low-risk?

Answer: It depends on the patient's history and whether you think the patient has coronary disease. As such, the decision depends on your assessment of the likelihood that the patient has ACS at all. If it is atypical pain, and/or a low likelihood, and the patient is otherwise a low risk, then they could be discharged. It should be noted that the TIMI risk score was developed among patients with a good clinical history of ACS, and even in patients with a TIMI score of 0 to 1, there is a 5% risk of an adverse cardiac outcome within 14 days. Moreover, 2% to 5% of ACS cases are missed in the ED.^3,4 Ask yourself whether the patient's history and symptoms fit with ACS, or do they suggest a more benign etiology, such as musculoskeletal pain or gastroesophageal reflux? If you think the patient has ACS, even if the TIMI score is 0, admit them to the observation unit and order a stress test.

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REFERENCES

1. Karha J, Gibson M, Murphy SA, DiBattiste PM, Cannon CP; for TIMI Study Group. Safety of stress testing during the evolution of unstable angina pectoris or non–ST-elevation myocardial infarction. Am J Cardiol. 2004;94:1537-1539.

2. Anderson JL, Adams CD, Antman EM, et al. ACC/AHA 2007 guidelines for the management of patients with unstable angina/non ST-elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2007;116(7):e148-e304.

3. Christenson J, Innes G, McKnight D, et al. Safety and efficiency of emergency department assessment of chest discomfort. CMAJ. 2004;170:1803-1807.

4. Pope JH, Aufderheide TP, Ruthazer R, et al. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med. 2000;342(16):1163-1170.

"Dr. James Hoekstra was very professional and informative. He did an excellent job in explaining to me the different, specific measures that could be used to improve the care of patients with ACS. This was the best peer-to-peer CME activity I have participated in. Thanks MED-IQ staff and Dr. Hoekstra" — Cardiologist, Illinois

This activity is supported by an educational grant from sanofi-aventis U.S.

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