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 third of these e-briefs; in this installment, our expert faculty answer some difficult questions about risk stratification posed by participants in our peer-to-peer teleconferences.

Despite specific ACC/AHA guideline recommendations on unstable angina (UA)/non-ST-segment elevation myocardial infarction (NSTEMI) risk stratification in the emergency department, the reality is that many situations are not “cut-and-dry” and require using good clinical judgment for accurately assessing risk. In the last e-brief, we answered questions about challenges in risk stratification; this e-brief addresses more of these difficult questions.

Interpreting Abnormal ECGs in Asymptomatic Patients With Diabetes
Question: In an asymptomatic patient with diabetes who presents to the hospital for reasons unrelated to ischemia, how should we interpret an ST-segment depression that is greater than 1mm on a routine ECG?

Answer: Diabetes is a major risk factor for coronary artery disease, and as many as 22% of patients with diabetes have silent myocardial ischemia.¹ Moreover, a number of studies have suggested an association between diabetes and unrecognized myocardial infarction (MI).² It may be that diabetic autonomic neuropathy plays a role in decreasing pain sensation from ischemic myocardium.² Thus, the finding of new ST-segment depression on a routine ECG in a patient with diabetes likely warrants further investigation. It would be wise to obtain a set of troponin levels; if positive, admission to the hospital for further evaluation with cardiac catheterization is likely to be indicated. If troponin is negative, it is reasonable to order a nuclear imaging stress test or refer the patient for a cardiology consultation.

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Using Risk Stratification When Medical History Isn't Available
Question: Calculating a TIMI risk score presumes that a patient's medical history—including coronary artery disease risk factors and prior coronary stenosis—are known. What is the best approach for risk stratifying patients in whom a complete medical history is not known?

Answer: Fortunately, a patient's medical history isn't required for some of the most critical elements of risk stratification: serial ECGs, serial cardiac biomarkers, and recent history of symptoms.³ Patients with ST-segment elevation myocardial infarction (STEMI)—a comparatively straightforward diagnosis—are a group in whom immediate reperfusion is necessary. For patients with UA/NSTEMI, risk stratification is used to decide whether an invasive strategy is appropriate (with catheterization in the next 24 to 48 hours for high-risk patients).³ For patients in whom a medical history is unobtainable, this window of time gives clinicians an opportunity to observe the patient's symptoms, obtain serial ECGs and cardiac biomarkers, and get additional medical history from other sources. If the ECG and troponin levels remain normal or nondiagnostic and the patient is clinically stable after 6 to 8 hours of observation, the patient's risk is likely to be low or intermediate. If there is still uncertainty, particularly in patients who appear to be at intermediate risk, a nuclear imaging stress test is a logical next step. Moreover, while waiting for results from cardiac biomarker testing, the patient may be safely started on antiplatelet and antithrombin therapy.³

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Interpreting Declining Troponin Levels
Question: In a patient with an initial slight elevation in troponin (eg, 0.08 ng/mL where the upper limit of normal is 0.04 ng/mL), what is the significance of this elevation if the next serial measurement shows that the troponin level is trending downward?

Answer: Cardiac troponin is highly specific for detecting myocardial cell necrosis.³ In MI, troponin may be detected in the blood as soon as 4 hours after an event, although this is sometimes delayed up to 12 hours. Troponin elevation generally persists for 5 to 14 days after an event.³ An initial elevation of 0.08 ng/mL would typically put a patient in the intermediate- to high-risk category; however, if the next serial troponin level showed no elevation, it could be that the initial elevation was a laboratory artifact. A slight troponin elevation that decreases on serial measurements would also be unusual, given the relatively long persistence of troponin in the blood after an event. Nevertheless, it is possible this trend represents myonecrosis. If other causes for elevated troponin can be ruled out (eg, sepsis, congestive heart failure), stress testing or an angiogram may be indicated.³

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REFERENCES

1. Wackers FJ, Young LH, Inzucchi SE, et al. Detection of silent myocardial ischemia in asymptomatic diabetic subjects: the DIAD study. Diabetes Care. 2004;27(8):1954-1961.

2. Sheifer SE, Manolio TA, Gersh BJ. Unrecognized myocardial infarction. Ann Intern Med. 2001;135(9):801-811.

3. 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.

"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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