Low risk chest pain evaluation - PowerPoint Presentation

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Low risk chest pain evaluation

‘Is that cardiac chest pain?’

Peter

Llewellin

August 2011

Revised July 2016

Background

Chest pain common presentation (10% ED visits

)

ACS only small proportion of this (~10

%)

STEMI normally obvious

(but not always!)

NSTEACS more difficult to

identify

Chest pain assessment (Emergency)

vs

Acute coronary syndrome assessment (Cardiology)

Failure to diagnose associated with 2-3x mortality rate

Evaluating the ‘low risk’ patient

Clinical features – Symptoms/Cardiac risk

profile/Exam

ECG

Cardiac

biomarkers

Clinical decision scores/Chest Pain

Units

Cardiac testing – MPS/EST/Stress Echo/CTCA

Chest pain - Symptoms

TYPICAL

pain helpful but not conclusive

‘Pressure' OR 2.0; pain radiating to R arm more specific than pain to L arm

!

Duration may be more useful - >10

min.

and relieved by rest more suggestive. Momentary pain (seconds) much less suggestive

.

Only 35% of ACS related to

exertion

Response

to nitrates NOT helpful



66% non cardiac pains shown to respond to

nitrate

therapy.



73

%

of all chest

pains respond to GI cocktail regardless of cause

!

Chest pain - Symptoms

ATYPICAL pain –

undefined !

‘Sharp/stabbing pain’ – 5%

AMI

‘

Costochondritis

’ – 6%

AMI

Bought on by stressful event – 8.2%

AMI

Bought on by eating – 6.8%

AMI

‘Burning/indigestion/epigastric’ pain –

equivalent risk

to ‘dull/pressure’

pain

Sharp pain/reproducible on exam + no

hx

CAD

TOGETHER

could rule out ACS

Chest Pain - Symptoms

Chest pain - Symptoms

25% of

all

ACS may be

SILENT

1/3 of

recognized

infarcts do not have chest/arm/throat

pain

Commonest non-pain symptoms =

dyspnoea

, nausea, diaphoresis,

syncope

Atypical = typical

in >75, female,

diabetic,

hypertensive

.

Chest pain – Risk factors

Traditional cardiac risk factors derived from Framingham

study

Determine risk long term,

not acutely

.

20% of AMI’s presented with NO risk

factors

Studies done on ED pts show only moderate effect on acute

risk

Age < 40 - 0 risk factors =ACS RR 0.17

- 4+ risk factors=ACS RR 7.4

Age 40-65 - 0 risk factors =ACS RR 0.53

- 4+ risk factors=ACS RR 2.1

Over 65, risk factors

had no impact

on acute risk of ACS

Chest pain – Exam findings

Generally

unhelpful

4

th

heart sound most common finding – statistically difficult to prove as useful

Role of examination is to find rule-in alternate diagnoses

The ECG

ECG is quickest and highly reliable way of ruling-

IN

ACS (70-85% specific

)

Both diagnostic and prognostic – increasing T wave deflection worsens mortality rate in

NSTEACS

Normal ECG at presentation does not rule-

OUT

ACS

Retrospective study on AMI showed 7.8% ECG

normal

at presentation, 35% ‘non-specific’

changes

‘Normal’ ECG interpretation highly associated with missing ACS diagnosis

The ECG

Any new ECG changes should be considered highly significant (and are associated with increased risk

)

ECG represents ‘snapshot’ of heart – serial ECG’s ‘highly recommended

’

ACS dynamic process – repeat ECG’s useful in suspect

patients

ST segment monitoring however of limited benefit in low risk population when studied

Cardiac biomarkers

Have been around since

1950

Clinical significance not appreciated until

1970’s

Unable to be refined for clinical use until late

80’s

AST

, LDH, CK now historical interest

only

CK-MB first to be studied as stratification aid – still features in some

protocols

Troponin gold standard – extensively studied for diagnosis and stratification

Cardiac biomarkers

NEJM

1996

Two large studies conclusively show that both Trop I and T elevated early in high risk

ACS

Predictive of 30-42 day

mortality

Predictive even in absence of CK-MB elevation or ECG features suggestive

ischaemia

Cardiac biomarkers

Incorporated into decision rules and

CPU’s

‘high sensitivity’ troponins now replacing previous generation

tests

Aim

to increase sensitivity to 99

th

percentile of normal population

Allows earlier detection of troponin elevations (?at 3

hrs

)

Have

mild-moderate decrease

in

specificity

(88-93%)

Overcome

by measuring ‘rise and fall

’ over 3-6

hrs

Clinical decision rules

Attempt to tie all aspects of assessment together to quantify

risk

PURSUIT; AHCPR; GRACE; TIMI

scores

All

incorporate elevated cardiac markers, ECG deviations and historical

information

These rules originally derived as Cardiology ‘rule-in’ guides for identifying higher risk patients

More recently rules developed in ED as ‘rule-out’ CDR’s to assess who requires further evaluation

HEART; EDACS; MACS; ADAPT scores

HFA/CSANZ rule incorporated in NSW chest pain pathway

HEART vs TIMI

Rule performance

Provocative testing

Aim is to stratify low risk patients to very low

risk

Usually added to a decision rule to form a Chest

P

ain

D

iagnostic

P

athway

Choices of provocative or diagnostic test

 Exercise treadmill test

 Stress Echo test

 Myocardial perfusion scanning

 CT coronary angiogram

Provocative testing

T

esting low pre-test probability individuals with tests of imperfect sensitivity/specificity

Pre test probability ~ 4-5 %

5% False +

ve

rate

Therefore ’positive’ result on provocative test = <50% chance of

actual

disease

CTCA/MPS added issue of radiation exposure (~8mSV)

EST – Sn 68%

Sp

77%

MPS – Sn 89%

Sp

73%

StressEcho

– Sn 85%

Sp

77%

CTCA – rule out ; 98-99% NPV if no calcium found

5% False positive rate with MPS/Stress echo

Chest pain pathway

30 day event rate MACE with negative ADP

: 0.5 – 1.5 %

1

yr

event rate

MACE with

negative ADP

low: <1-2%

3

yr

event rate

MACE : 5-15

%

Warranty period of negative provocative testing/ADP?

Negative angiogram 1yr event rate

1.2% (mild CAD 3.3%)

Summary ‘Low risk patients’

Cardiology and Emergency; Rule-in vs Rule-out philosophy

..

No

single

piece of clinical information helpful

.

Don’t rely upon ‘risk factors profile

’

Beware the elderly, the diabetic, the hypertensive and the female (especially if all of the above

!)

Most patients need

provocative

test

to lower risk to <1% BUT these are

far

from perfect

Get comfortable with a

1%

miss

rate !