Acute Coronary Syndrome: GP Essentials

Spencer Toombes FRACP

Learning Plan...

Challenges of assessing patients with chest pain...

Terminology & Pathophysiology ECG interpretation Use of Troponin Risk Assessment Inpatient management

- how and when to transfer Post-discharge management

5 min task in pairs:

For each of the following scenarios...

What is the most likely diagnosis?

What is this patient’s risk of having an Acute Coronary

Syndrome?

68 yo man:

Complaining of intermittent central chest pain.

Previous ischaemic heart disease:Coronary angiogram 2 years ago showed 40% LAD and 30% RCA stenosis.

Managed medically.Has noticed over the past 2 months

that he needs to use his GTN spray whenever he exerts himself.

The same 68 yo man:

What if he had received a stent 5 months ago?

68 yo woman:

Recent sharp, stabbing pain adjacent to her left sternum.

There doesn’t seem to be a clear precipitant.

She feels a bit washed out, but otherwise reasonably well.

…but she is a Type II diabetic.

46 yo man:

10 minutes of central chest heaviness after he finished mowing the lawn

Associated with pallor and breathlessness

His wife thought he looked ill and talked him into coming up to your practice.

Positive family history, heavy smoker.

Differential Diagnosis of Chest Pain:

(Includes biliary)

Prevalence of MSK chest Pain:Depends on the site at which you study!

Cardiac vs Oesophageal Chest Pain:is not distinguished by Site of Radiation

Bennett et al. Lancet. 1966

Cardiac

100%37%

12%

Back 12%

28%

49%35%

60%

Oesophageal

100%23%10%

14%

5% 18%

Back 33%

33%

More difficulties in evaluating the Patient with Chest Pain: Intensity of Pain - no indication of severity.

Nature of Pain - no indication of diagnosis:• 5-19% acute coronary syndromes ‘sharp’ or pleuritic.

Physical Signs - no indication of diagnosis:• 15% AMI patients have chest wall tenderness.

‘Atypical’ Presentations:• Up to 25% patients with ACS do not present with

“classical” chest pain.

Terminology: define in pairs...Acute Coronary Syndrome (ACS)Stable anginaUnstable anginaMyocardial ischaemiaQ wave infarctionNon-Q wave infarction STEMI... STEACSNon-STEMI... Non-STEACS

Pathophysiology:Components of atheroma plaque -

Pathophysiology:Safe or Stable plaque:

little cholesterol content thick fibrous cap low risk of rupture

The proportion of the lumen occluded determines the degree of exercise related ischaemia, and the severity of symptoms.

Safe Plaque - Chronic Stable Angina

Pathophysiology:Unsafe / Unstable Plaque

Lots of Low Density Lipoprotein Cholesterol

Thin fibrous cap Lots of inflammation:

Activated T cells, Macrophages, Foam Cells Mediators: Cytokines and C reactive

protein

HIGH RISK OF RUPTURE

Unsafe Plaque - Potential for trouble!

Acute Coronary Syndromes:Plaque rupture: Acute clot formation.

ACS / Dynamic Clot formation:Spectrum of Possible Outcomes -Dynamic Partial Occlusion: No

damage Worsened Angina pain, possible ECG change No cardiac enzyme rise

Dynamic Partial Occlusion: Some damage Worsened Angina pain, probable ECG change Rise in cardiac troponin, +/- creatinine kinase

Complete Occlusion: Full thickness myocardial infarction ST segment elevation, Q wave formation if not

treated

TroponinTroponin

No detectableNo detectabletroponintroponin

Normal CKNormal CK

DetectableDetectabletroponintroponin

Normal CKNormal CK

DetectableDetectabletroponintroponin

and elevated CKand elevated CK

nono Q waveQ wave Q or no Q waveQ or no Q wave

Normal ECGNormal ECG ST depressionST depressionor transient ST elevationor transient ST elevation

Serum markersSerum markers

ECG at evaluationECG at evaluation ST elevationST elevation

ECG at dischargeECG at discharge Normal ECGNormal ECG

CKCK

ST Elevation ST Elevation MIMI

LowLow--riskriskUAPUAP

HighHigh--riskriskUAPUAP“minor“minor

myocardialmyocardialdamage”damage”

NonNon--ST ST ElevationElevation

MIMI

Acute Coronary Syndrome : TerminologyAcute Coronary Syndrome : Terminology

Chest Pain: Getting the basics right...

Rapid assessment.Observed environment.

Aspirin 300mg.

ECG within 10 minutes of presentation.

12 Lead ECG interpretation:

STEMI: requires immediate reperfusion

Everything else: still requires risk assessment.

Or maybe it looks like this...

ActinTropomyosin

Tnl TnC TnTCa++

Cardiac Troponin Complex:

Cardiac Troponin:

Exquisitely sensitive marker of myocardial distress... not necessarily muscle necrosis

Onset 4-6, peak 24-36 hours, offset 7 days

Normal initial troponin is NOT reassuring

Normal 12 hour troponin is quite reassuring

Risk Stratification using ECG & Tn testing (mod. from NEJM 337:1648-53)

Troponin T and probability of death

Lindahl NEJM 2000 343:16;1139-47

Practice Points: Troponin

Don’t necessarily mean ACS... Pulmonary embolus Left ventricular failure Renal failure Sepsis

True false positives related to assay Immune cross reactivity

Practice Points: Troponin

GENERALLY DO NOT ORDER

IN GENERAL PRACTICE

Diagnosis of ACS evolves over time…

Time

Evolution of ECG and

biomarkers

Final diagnosis

Working diagnosis

Presentation of ACS(clinical presentation, initial ECG)

STEMI NSTEACS

NSTEMI Unstable anginaSTEMI

Myonecrosis confirmed Myonecrosis not confirmed

ACS = acute coronary syndromes; ECG = electrocardiogram; STEMI = ST-segment-elevation myocardial infarction; NSTEACS = non-ST-segment elevation acute coronary syndromes; NSTEMI = non-ST-segment elevation myocardial infarctionAcute Coronary Syndrome Guidelines Working Group. Med J Aust 2006;184(8 Suppl):S9-29.

68 yo man:

Complaining of intermittent central chest pain.

Previous ischaemic heart disease:Coronary angiogram 2 years ago showed 40% LAD and 30% RCA stenosis.

Managed medically.Has noticed over the past 2 months

that he needs to use his GTN spray whenever he exerts himself.

68 yo woman:

Recent sharp, stabbing pain adjacent to her left sternum.

There doesn’t seem to be a clear precipitant.

She feels a bit washed out, but otherwise reasonably well.

…but she is a Type II diabetic.

46 yo man:

10 minutes of central chest heaviness after he finished mowing the lawn

Associated with pallor and breathlessness

His wife thought he looked ill and talked him into coming up to your practice.

Positive family history, heavy smoker.

For each of these patients:

What is their risk of having an Acute Coronary

Syndrome?

These patients can be managed with upgrade to their anti-anginal medications and outpatient referral for cardiac investigation.

These patients generally require emergency admission to a monitored environment, and aggressive drug therapy including parenteral anticoagulants.

These patients generally require a period of observation with serial ECG and biomarker assessment, enabling them to be re-classified as high or low risk...

Transfer to hospital:

Ambulance

Monitoring

Oxygen ?Nitrates ?Aspirin ? Pain relief ?

What happens in hospital?

Intermediate risk: reclassify after 6-12 hours

Low risk:Upgrade therapy?Provocative investigation: EST or MPS

High risk...

High Risk - Non-STEACS management:

Anti- Platelet agents…Aspirin 300mg. stat. then 75 -

100mg. daily.Clopidogrel: 300mg. load then

75mg. dailyGp IIbIIIa receptor antagonists:

Tirofiban (Aggrastat) Abciximab (Reopro) Eptifibatide (Integrilin)

Where the anti-platelet agents fit in...

COX, cyclooxygenase; ADP, adenosine diphosphate; TxA2, thromboxane A2

Schafer AI Am J Med 1996;101:199–209

CLOPIDOGREL

ASA COX

ADP

ADP

C

GPllb/llla(Fibrinogen receptor)

Collagen thrombinTXA2

Activation

TXA2

Furie B and Furie B. N Engl J Med 2008;359:938-949

Pathways of Blood Coagulation during Hemostasis and Thrombosis

Non-STEACS management: Anticoagulants...

IV unfractionated heparin infusion

s/c low molecular weight heparin(eg. Clexane 1mg./kg. bd.)

s/c Fondaparinux (Erixtra)

High risk Non STEACS Management - additional proven therapeutics:

Beta blockers, IV and/or oral. Insulin + dextrose infusion for

high BSL. High dose Statins: eg. 80mg.

Atorvastatin ACE inhibitors Oxygen Morphine & Nitrates for symptom

control

Non-STEMI management:Routine Early

Angiography…

Evidence supports prompt routine angiography with a view to angioplasty of the culprit lesion.

▪ TACTICS TIMI18, FRISC II, RITA 3▪ ICTUS ???

STEMI Managment:Thrombolytics: - time is muscleFTT collaboration group, LANCET 343:311-22 (1994)

Lancet Meta-analysis:Primary PCI vs. Thromblysis

Short term death 7% vs. 9% STD excld. SHOCK 5% vs. 7%

Reinfarct rates 3% vs. 7% CVA 1% vs. 2%

Combined endpoint 8% vs. 14%

Ischaemic Heart Disease?What patients should go home

on…

Cardiologists drive SAABs:S tatin (high dose atorvastatin)A nti platelet agents: Aspirin +

ClopidogrelA ce inhibitorB eta-blocker

Return to Function:

Sexual Relations: 6-7 METS: Stage II Bruce, 2 flights stairs

Driving: (private license) Angioplasty: 2 days, assuming no MI, no

symptoms and normal ecg. Myocardial Infarct: 2 weeks, assuming

uncomplicated Cardiac Arrest: 6 months, unless assoc.

MI

Summary:

Assessing chest pain is notoriously difficult

Early aspirin, Early ECG

If in doubt, manage as an inpatient

Risk stratification, with serial data

Aggressive drug combinations for high risk patients... Anticoagulants, and Antiplatelets.