1. Acute Management of Myocardial Infarction

2. Introduction Stable angina Acute coronary syndrome STEMI NSTEACS
NSTEMI
Unstable angina

3. Introduction
Stable angina arise when lumen stenosis >70% → impaired blood supply to heart only during on exertion or increased metabolic demand
Acute coronary syndrome arise when vessel becomes occluded by thrombus
Unstable angina – when atherosclerotic plaque shoot of embolus downstream to cause microinfarct
NSTEMI – when necrosis confined to endocardial layers (most susceptible to ischaemia)
STEMI – when full thickness necrosis of the ventricular wall occurs

4. Introduction Stable angina – normal ECG, normal troponin
Unstable angina – normal troponin
NSTEMI – elevated troponin
STEMI – elevated ST segment
Criteria for thrombolysis or PCI (i.e. STEMI)
>1mm elevation in 2 contiguous limb leads
>2mm elevation in 2 contiguous precordial leads
New onset LBBB

5. History
All causes central crushing chest pain or tightness radiating to arm, neck and jaw
Stable angina usually last less than 20 minutes, precipitated by exertion and relieved by rest or nitrates
ACS usually lasts more than 20 minutes, sudden onset usually at rest and not relieved by rest
All associated with sx of ↓cardiac output – SOB, presyncope or syncope, palpitations
All associated with sx of sympathetic activation – nausea, vomiting, sweating, pale, clammy
All associated with risk factors – HTN, high cholesterol, DM, smoking, family history

6. Examination Usually no signs
Signs of precipitants (e.g. anaemia, infection, thyrotoxicosis, arrhythmias), risk factors, other atherosclerotic diseases (PVD, stroke), complications (e.g. MR, CHF)

7. Investigations Resting ECG (on arrival) Stable angina – normal
Unstable angina or NSTEMI – ST depression or T wave inversion
STEMI – ST elevation → Q wave (permanent) → T wave inversion (in this order)
Cardiac enzymes – Troponin, CKMB/CK ratio, AST, LDH
Stable angina and unstable angina – normal
NSTEMI, STEMI – raised

8. Investigations FBE – anaemia, infection
UECR, coagulation study – ability to take contrast and undergo PCI
FBG, lipid profile (within 24h) – DM, hypercholesterolaemia
CXR – r/o aortic dissection, pneumonia, pneumothorax, interstitial lung disease

9. Investigations Note: Troponin vs CKMB
CKMB – rise in 4hr, elevated for 72hr
Trop – rise in 8hr, elevated for 5 days (trop I) and 10 days (trop T)
If trop –ve → repeat in 8hr → last serial trop done 8hr after sx resolves
CKMB can be used to detect second infarcts

10. Acute Management Oxygen therapy GTN (½ sublingual tab) Aspirin 300mg
IV morphine 2.5~5mg + IV metoclopramide 10mg

11. Hospital Management
Aspirin, GTN, morphine, oxygen if not already given
Monitor oximetry, BP, continuous ECG
12 lead ECG, IV access, cardiac enzyme

12. STEMI
Reperfuse ASAP (within 12hrs of onset of sx – i.e. before MI is complete):
Antiplatelet therapy (aspirin and clopidogrel ± GPIIb/IIIa inhibitor)
Anticoagulation agent (unfractionated heparin or LMWH)
Immediate PCI or fibrinolytic therapy – PCI has higher reperfusion rate and is better if pt present > 1hr but thrombolysis is gold standard if pt arrive within an hour

13. STEMI Subsequent management (start during this hospital admission)
Statins, aspirin and clopidogrel, ACEI (or ARB), β-blocker (if CI then CCB)
Anticoagulation therapy to prevent thromboembolism (warfarin for 6mos if large anterior MI, esp if echo show large akinetic/dyskinetic area, aneurysm or mural thrombus)
Nitrates PRN
Cardiac rehabilitation
Antiplatelet post stent
Aspirin for life
Clopidogrel for at least 6wks for metal stent
Clopidogrel for at least 12mos for drug eluting stent
Drug eluting stent have lower early re-stenosis rate c.f. bare metal stent however have a problem of late thrombosis

14. UA and NSTEMI Stabilize acute coronary lesion
Anti-platelet (aspirin and clopidogrel ± GPIIb/IIIa inhibitor)
Anti-thrombin (UFH or LMWH)
Anti-ischaemia (β-blocker if CI then CCB, consider nitrates, morphine)
High risk – urgent angiography ± PCI
Low risk – arrange stress tests
Subsequent management (start during this hospital admission)
Statins, aspirin and clopidogrel, ACEI (or ARB), β-blocker (if CI then CCB)
Nitrates PRN
Cardiac rehabilitation

15. Risk Stratification TIMI Score (Para Sea) Historical
PHx – known CAD (stenosis ≥ 50%)
Age>65
≥3 RFs for CAD
Aspirin use in past 7d
Presentation
ST segment deviation ≥0.5mm
↑cardiac enzymes
Recent (≤24hr) severe angina

16. Risk Stratification Risk stratification of NSTEACS – “HEART DOC”
Haemodynaic compromise
ECG changes
Arrhythmia
Renal failure
Troponin rise
Diabetes mellitus
Ongoing chest pain
Cardiac bypass anytime or PCI in last 6months
Having 1 of these → high risk group

17. Stable Angina Statins, aspirin (or clopidogrel), ACEI, β-blocker
Nitrates – sx relief or prophylaxis (patch or tablets but must have 8h nitrate free period/day)
Wholistic care (all IHD):
Lifestyle change – quit smoking, eat healthy, exercise more, avoid excessive exertion or stress
Risk factor control – HTN, high cholesterol (keep <4mmol/L), DM
Assess depression, level of support

18. Summary
MOAN
ECG, troponin, R/O DDx
Code AMI
Reduce time to PCI

19. Quiz 1 - Complications Early (0~48h)
Any arrhythmias – worry about AF, VT, VF, CHB
LVF → cardiogenic shock
Medium (2~7d)
Rupture of papillary muscle (→MR), IV septum, LV wall → acute cardiac failure → APO → death
Late (>7d)
Cardiac failure
LV aneurysm → mural thrombus → thromboembolism
Dressler’s syndrome (3~8wk) – recurrent pericarditis following AMI
(Hence why β blockers given initially → prevents arrhythmia as well as rupture of cardiac muscle)

20. Quiz 2 Contraindication for thrombolysis
Past allergic reaction, past streptokinase use
Past stroke – haemorrhagic (ever), ischaemic (6mos)
Brain tumour/trauma
Recent bleeding or risk of bleeding – e.g. GI bleeding, liver disease
Recent surgery
Hypertension
Pregnancy

21. Quiz 3
PCI vs CABG
Advantage of PCI – less invasive, less peri-operative stay, morbidity and mortality
Advantage of CABG – higher chance of revascularization
PCI over CABG – single or double vessel disease, inability to tolerate surgery
CABG over PCI – triple vessel disease or left main disease, diabetes mellitus, failed PCI