Troponin = 35. Objectives. Low Risk Chest Pain. Does this patient have ACS? Does this patient have ACS? Objectives

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1 Objectives Low Risk Chest Pain Jeffrey Tabas, MD Professor of Emergency Medicine Office of CME UCSF School of Medicine 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 Does this patient have ACS? Does this patient have ACS? Troponin = 35 Objectives 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 ACUTE CORONARY SYNDROME The first problem Acute Myocardial Infarction and Unstable Angina are 2 different diseases with 2 different workups! It s sort of like choledocolithiasis and cholecystitis 1

2 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] Was AMI appropriately excluded? 1. Yes 2. No 3. Care is never appropriate at a conference 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%) 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 2

3 TIMI Modified TIMI GRACE FRISC HEART Risk Scores Most derived from pts with definite ACS, not possible ACS (except HEART) Based on 1 st troponin - Aren t we interested after 2nd? TIMI Risk Score TIMI = 0 has sensitivity of 96.6% ( %) - Hess, AEM, 2010 None of the following Age 65 or more 3 or more CAD risk factors Known CAD (stenosis >50%) ASA use in past 7 days Severe angina (>= 2 episodes w/in 24 hrs) ST changes >= 0.5 mm Positive initial cardiac marker Simplest Low-risk Score Risk of events 2% or less Negative initial cardiac marker Near normal ECG 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 It s about the troponins AMI exclusion is something we can and should do correctly ACEP Clinical Policy Annals EM, Sept 2006 AMI: ACEP Policy 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 SFGH Protocol for ECG and Troponin Testing If symptoms are unchanging or resolved Check at arrival and at 6 hours from ONSET (not 6 hrs after arrival!) E.g. Onset 2hrs prior to arrival, check on arrival and at 4 hrs E.g. Onset 6 hrs prior to arrival, check only on arrival If symptoms are stuttering Check on arrival, at 3 hrs, and at 6 hours 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? Understanding the Lab Understanding the Lab Assay limit of detection < th percentile = 0.10 <0.01 = Undetectable 0.01 to 0.1 = Detectable (but within normal range ) > 0.1 = Elevated 10% coefficient of variance (imprecision) = 0.3 4

5 Troponin Leaks Acute Troponin Leaks Aviles and Aviles, EM Clinics, 2005 Tachycardia CHF PE Peri/Myocarditis Renal Failure DKA Sepsis Newby L, JACC 2012 Saunders JT, Circ 2011 Any detectable Troponin level is associated with markedly increased adverse event rate over time Troponin Leak Pearls More rapid ED rule outs? 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 Highly sensitive Troponins More rapid ED rule outs? Keller et al, JAMA, Dec patients in Germany, 23% with AMI Highly Sensitive Trop on arrival: Sens = 100% (for level of detection) Standard Trop 3 hrs post arrival: Sens = 98.2% (for level of detection) Current Troponin Assays - Summary Any detectable level mandates further evaluation - Repeat level and stress testing is safest approach Although not yet in the guidelines, an undetectable level at 0 and 3 hrs excludes AMI 5

6 Super Sensitive Assays - Summary Any detectable level mandates further evaluation - Repeat level and stress testing is safest approach With Highly Senstive Troponins, a 0 and 1 hr level excludes AMI As sensitivity increases, we will get an increasing number of false positives Ways to miss AMI w/ a negative 6 hr Trop 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 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 Does Prior Stress Testing Exclude ACS? MI evolves most frequently from plaques that are only mildly to moderately obstructive the risk of plaque disruption depends more on plaque composition and vulnerability (plaque type) than on degree of stenosis (plaque size). Value of prior stress 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 Falk, et al. Circulation,

7 Lessons from Treadmill testing 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 Outpatient Noninvasive Testing in 72 hours? Anderson, Circ, 11 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 CT Coronary Angio: The Future? 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 1000 pts w/o CAD, ischemic ECG or initial positive Tn Randomized to CTCA or usual care 2% AMI, 5% UA Mean LOS reduced by 7.6 hours (P<0.001) More D/C s directly from ED: 47% vs. 12% (P<0.001) However, even at 1 year, CTCA vs Usual Care resulted in more tests, more radiation (14 msv vs 5 msv), and more interventions (32 vs 21) 7

8 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?) 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 DO what you and the patient believe is best How Can We Detect All ACS? How Do We Manage Our Low Risk Chest Pain Patients? DOCUMENT their understanding of the risks of the decision, which are always present 8

9 A Sample Approach - Conservative TIMI = 1 or more Negative initial Troponin and ECG CTA or admit to cardiology TIMI = 0 Negative Troponin and ECG at 0 and at least 8 hours after onset Stress test while in ED or as outpatient if unavailable A Sample Approach - Liberal Rule Out AMI Non-ischemic ECGs and Negative cardiac markers at least 6 hours from symptom onset Exclude UA (non-invasive testing) In ED If symptoms intermittent or short duration (and somewhat consistent with anginal pain) Discharge Accelerated Outpatient stress testing MD followup 54 y.o. M w/ left shoulder ache x 8 hours. Nl exam and ECG Single 8 hr TnI sent = 0.09 [ ng/ml] Documentation 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 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 hours after onset in a patient with a non-ischemic ECG A negative troponin at 3 hours after arrivaol with a nonischemic ECG 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 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 9