Low Risk Chest Pain. Objectives. Disclosure. Case 1. Jeffrey Tabas, MD Professor of Emergency Medicine Office of CME UCSF School of Medicine

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1 Disclosure Low Risk Chest Pain No Financial Relationships to Disclose No significant investments or savings Unlimited Expenses Jeffrey Tabas, MD Professor of Emergency Medicine Office of CME UCSF School of Medicine Objectives Case 1 Improve speed and accuracy in assessing patients with possible ACS! Avoid pitfalls in the use of cardiac markers to exclude AMI Avoid pitfalls in the use of noninvasive testing to exclude Unstable Angina 54 y.o. M w/ left shoulder ache x 8 hours. Only hx is smoking ¼ ppd Normal exam except marked Left trapezius muscle spasm ECG no ischemia CXR Normal Single 8 hr TnI sent = 0.09 [ ng/ml] 1

2 Case 1 Case 1 Was AMI appropriately excluded? 1. Yes 2. No 3. Care is never appropriate at a CME lecture What about Unstable Angina? Other diagnoses? Discharged with Dx of shoulder strain and follow-up by PMD in 1-3 days. Patient is brought back 12 hours later in cardiac arrest A lawsuit is brought and settled out of court Steps in Assessment of ACS 1. Risk Stratify 2. Rule out MI 3. Rule out UA Immediate Delayed How do ACS patients present to our EDs? Gupta, Ann EM cases of AMI CHEST PAIN NO CHEST PAIN (53%) (47%) Shortness of Breath (17%) Cardiac arrest (7%) Dizzy/Weak/Syncope (4%) Abdominal Pain (2%) Other (17%) 2

3 How do ACS patients present? - Summary - 50% of patients with ACS present like the text books say 50% of patients with ACS present atypically Atypical is TYPICAL AMI : The Cardiac Markers In a patient without ischemia on ECG, it s all about the troponins! AMI exclusion 6 hours after ONSET is accepted although repeating a level 6 hours after ARRIVAL is common AMI exclusion 2-3 hours after ARRIVAL is here (but hasn t reached the guidelines yet) Excluding AMI AMI: ACEP Policy It s about the troponins AMI exclusion is something we can and should do correctly ACEP Clinical Policy Annals EM, Sept 2006 A negative cardiac marker at least 8 hours from symptom onset OR A negative 90 min delta myoglobin + (CKMB or Troponin) OR A negative 2 hr delta CK-MB + Troponin 3

4 Morrow, Circ, 07 What is a Low Risk Patient? No Ischemia on ECG Initial Cardiac Marker is Negative AMI: Lab Medicine A negative cardiac marker at least 6 hours from symptom onset IF Low Risk A negative cardiac marker at least 12 hours from symptom onset IF Mod-High Risk Case 1 Understanding the Lab 54 y.o. M w/ left shoulder ache x 8 hours. Nl exam and ECG Single 8 hr TnI sent = 0.09 [ ng/ml] Was AMI appropriately excluded? Assay limit of detection < th percentile = % coefficient of variance (imprecision) = 0.3 4

5 Understanding the Lab Troponin Leaks <0.01 = Undetectable 0.01 to 0.1 = Detectable (but within normal range ) > 0.1 = Elevated Aviles and Aviles, EM Clinics, 2005 Tachycardia CHF PE Peri/Myocarditis Renal Failure DKA Sepsis Acute Troponin Leaks Chronic Troponin Leaks Morrow, JAMA, 01 Even slight elevations (> 0.1) predict death and adverse events. TnI between 0.1 and 0.4 = 2.5 O.R. for death/mi Han et al, Am J Nephrol, of 107 asymptomatic dialysis pts with mild TnT elevation had 6 fold higher risk of cardiovascular events over 3 years 5

6 Troponin Leak Pearls Super sensitive assays It s a leak if: 1) They ve had it in the past (more than once) 2) You repeat and it doesn t rise NEJM, Aug Super Sensitive Assays - Summary Ways to miss AMI w/ a negative 6 hr Trop Any detectable level mandates further evaluation - Repeat level and stress testing is safest approach Not in the clinical policies yet, but pretty good evidence that with a sensitive assay, an undetectable level at 0 and 3 hrs excludes AMI As sensitivity increases, we will get an increasing number of false positives Unacceptable Miss the ischemic ECG Troponin not really negative (i.e detectable) Not really 6 hours after onset (stuttering) Acceptable Very tiny percentage of patients still have AMI We didn t miss AMI but unstable angina 6

7 Unstable Angina: Noninvasive Tests ED Treadmill Understand your non-invasive testing! Outpatient testing Sensitivity Specificity # of Patients Treadmill ,074 Nuclear stress Stress Echo Lee NEJM 01 Amsterdam, JACC, ED pts sent for treadmill w/ a single negative troponin Negative ETT in 64% = 0.2% Event Rate Positive ETT in 13% = 14% Event Rate Nondiagnostic in 23% = 3.6% Event Rate Value of prior stress testing? Lessons from Treadmill testing Nerenberg, AJEM, 07 Compared with no prior testing: A positive prior ETT increases admit rate and rate of adverse events A negative does NOT change admit rate or rate of adverse events A negative exercise treadmill excludes that the current symptoms are due to ACS Confirm that test is diagnostic 85% MPHR (> 6 mets, DP > 22.5 K) Non-diagnostic results need further eval Previous treadmill helpful only if abnormal 7

8 Outpatient Noninvasive Testing in 72 hours? CT Coronary Angio: The Future? Braunwald, Circ, 02 ACC/AHA Recommends noninvasive testing within 72 hours of ED visit Meyer, Annals EM Showed this was a safe strategy in 1000 low risk Kaiser patients after AMI rule out Radiation Doses Radiation exposure Yearly background = 3 CXR = 0.02 Cardiac cath = 6 Tc-99 Stress Mibi = 8 CTCA: Male = 9 msv (14 if retrospective) CTCA: Female = 12 (21 if retrospective) Smith-Bindman, Arch IM 09 - Actual Doses!!!! CTCA 22 (14-24) msv CT in ACS- My Take Excellent Negative Predictive Value Use only when treadmill unavailable or patient can t exercise Probably best for a moderate risk pt i.e. > 10% ACS risk Identifies other diseases! (Causes other diseases?) 8

9 How Can We Detect All ACS? How Can We Detect All ACS? The only way to detect all ACS is to test everyone! However, we have seen testing lead to wasted time, money, unnecessary complications and further testing due to non-diagnostic or false positive results DOCUMENT their understanding of the risks of the decision, which are always present DO what you and the patient believe is best Case 1 Implications 54 y.o. M w/ left shoulder ache x 8 hours. Nl exam and ECG Single 8 hr TnI sent = 0.09 [ ng/ml] Died of Aortic Dissection No CXR was obtained Documentation for chest pain should discuss both doctor s and patient s understanding of risk that is acceptably low but not zero for: Acute MI Unstable Angina Aortic Dissection Pulmonary Embolism 9

10 Summary Summary The exclusion of AMI and UA are two different processes. After excluding ischemia on ECG: AMI is about the troponins A negative troponin at 6-8 hours after onset Arrival and 3 hours with sensitive markers Beware detectable but non-diagnostic elevations Unstable Angina is about the Non-invasive testing Unstable Angina If using a treadmill, confirm the test is diagnostic 85% MPHR (> 6-10 mets) Non-diagnostic results require further eval It is acceptable to schedule expeditiously as outpatient Beware the previous negative treadmill, especially when symptoms were different 10