Troponin = 35 ACUTE CORONARY SYNDROME Objectives The first problem - - PDF document

2/5/2013 1

“Low Risk” Chest Pain

Jeffrey Tabas, MD

Professor of Emergency Medicine Office of CME UCSF School of Medicine

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 non-

invasive 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 non-

invasive 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

2/5/2013 2

Case 1

 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 [0.00 – 0.10 ng/ml]

Case 1

Was AMI appropriately excluded?

1.

Yes

2.

No

3.

Care is never appropriate at a conference lecture What about Unstable Angina? Other diagnoses?

Case 1

 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

• ut 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 2002 - 720 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%)

CHEST PAIN

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

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Risk Scores

 TIMI  Modified TIMI  GRACE  FRISC  HEART  Most derived from pts with definite ACS, not possible

ACS (except HEART)

 Based on 1st troponin - Aren’t we interested after 2nd?

TIMI Risk Score

TIMI = 0 has sensitivity of 96.6% (91.5-99%)

• 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)

 It’s about the troponins  AMI exclusion is something we can and should

do correctly

Excluding AMI

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

2/5/2013 4 Morrow, Circ, 07

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

 No Ischemia on ECG  Initial Cardiac Marker is Negative

What is a Low Risk Patient?

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

Case 1

 54 y.o. M w/ left shoulder ache x 8

hours.

 Nl exam and ECG  Single 8 hr TnI sent

= 0.09 [0.00 – 0.10 ng/ml] Was AMI appropriately excluded?

Understanding the Lab

 Assay limit of detection <0 .01  99th percentile = 0.10  10% coefficient of variance (imprecision) = 0.3

Understanding the Lab

 <0.01 = Undetectable  0.01 to 0.1 = Detectable (but within “normal range”)  > 0.1 = Elevated

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Troponin “Leaks”

Aviles and Aviles, EM Clinics, 2005

 Tachycardia  CHF  PE  Peri/Myocarditis  Renal Failure  DKA  Sepsis

“Acute Troponin Leaks”

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

It’s a leak if:

1)

They’ve had it in the past (more than once)

2)

You repeat and it doesn’t rise

More rapid ED rule outs?

NEJM, Aug 27 2009 Highly sensitive Troponins

More rapid ED rule outs?

 1818 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)

Keller et al, JAMA, Dec 2011

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

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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

 Understand your non-invasive testing!

Outpatient testing Sensitivity Specificity # of Patients Treadmill 68 77 24,074 Nuclear stress 88 77 628 Stress Echo 76 88 1174

Lee NEJM 01

ED Treadmill

Amsterdam, JACC, 2002

 1000 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).” Falk, et al. Circulation, 1995

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

• r rate of adverse events

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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)

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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?

DOCUMENT their understanding of the risks

• f the decision, which are always present

How Do We Manage Our Low Risk Chest Pain Patients?

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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

Case 1

 54 y.o. M w/ left shoulder ache x 8

hours.

 Nl exam and ECG  Single 8 hr TnI sent

= 0.09 [0.00 – 0.10 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

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 non-

ischemic ECG

 Beware detectable but non-diagnostic elevations

 Unstable Angina is about the Non-invasive testing

Summary

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