Chapter 4: Cardiac Causes of Cardiac Arrest

Question 1

How can acute coronary syndrome be split up?

Answer 1

STEMI

Non ST Elevated acute coronary syndromes:

• NSTEMI
• Unstable angina

Question 2

What can be used to determine between STEMI and NSTEMI?

Answer 2

ST elevation or new LBBB = STEMI

Other ECG changes = NSTEMI/Unstable angina

Question 3

How do you differentiate between unstable angina and NSTEMI?

Answer 3

Troponin release

Question 4

What may indicate that a non-ST elevated ACS may be high risk?

Answer 4

1. ST depression
2. Dynamic ECG changes (different from baseline)
3. ** Unstable rhythm**
4. Unstable haemodynamics
5. Diabetes
6. High GRACE score

Question 5

Which groups of people may present with ACS less typically?

Answer 5

Females
Elderly
Diabetics

Question 6

What are some atypical symptoms of ACS?

Answer 6

1. Indigestion type pain
2. Pain radiate to throat, into one or both arms, into back or upper abdomen
3. ASx

Question 7

What ECG changes can an NSTEMI/unstable angina show?

Answer 7

Normal
ST Depression
Non specific abnormalities - t wave inversion

Question 8

When is risk of progression from NSTEMI to full occlusion highest?

Answer 8

First few hours, days and months

Question 9

What is there a substantial risk of in the acute phase of a STEMI?

Answer 9

1. VF
2. VT
3. Sudden death

Question 10

What ECG changes may be seen in a STEMI?

Answer 10

1. ST elevation
2. New LBBB
3. Pathological q waves
4. T wave inversion
5. Hyperacute t waves (v early)

Question 11

How quickly do you aim to give PCI in a STEMI? What should you do if this can not be achieved?

Answer 11

Within 120 minutes of onset of chest pain

Fibrinolytic therapy

Question 12

Which leads indicate where an infarct may be?

Answer 12

Anterior - V1-4 = LAD
Inferior - II, III, AVF = RCA
Lateral - I, AVL, V5-6 = Left Circumflex
Posterior - Reciprocal changes to anterior (ST Depression in V1-4) = RCA

Question 13

What is important to know about posterior MI’s?

Answer 13

Must confirm with posterior leads

Risk of bradycardia as SAN may be affected

Question 14

What other conditions can cause acute ST depression or t wave inversion?

Answer 14

1. Subarachnoid haemorrhage
2. Traumatic brain injury
3. Major PE - t wave inversion

Question 15

Why is echocardiography useful in acute ACS?

Answer 15

1. Confirm LV systolic Fx - related to prognosis
2. Can prompt diagnoses of cardiomyopathy, valve disease, pericardial disease, aortic dissection and PE
3. Can confirm RV dilatation & impairment

Question 16

What are the GRACE and CRUSADE scores?

Answer 16

GRACE - predict risk of adverse outcome

CRUSADE - Risk of major bleeding during hospital admission following ACS

Question 17

Within what time frame should reperfusion be post STEMI without delay?

Answer 17

If presenting within 12 hours - PCI or fibrinolysis

Question 18

What anti-thrombotic therapy should patients having a PCI be given and what dose?

Answer 18

Aspirin 300mg + 1 of

• Clopidogrel 600mg
• Prasugrel 60mg (not if >75, <60kg or hx of bleeding/stroke)
• Ticagrelor 180mg

Anticoag with heparin is given in Cath lab - Bivalirudin is alternative

In high-risk, glycoprotein IIb/IIIa inhibitor may be given

Question 19

What are the typical indications for fibrinolytic therapy?

Answer 19

1 of:
- STEMI >0.2mV in 2 adjacent chest leads or >0.1mV in 2 adjacent limb leads

• Dominant R waves and ST depression in V1-3 (post MI)
• New onset LBBB

Question 20

What is given alongside fibrinolytic therapy for STEMI?

Summary Rx - 3 points

Answer 20

1. **Aspirin 300mg ** loading dose AND
2. Clopidogrel 300mg loading dose AND
3. Antithrombin therapy: LMWH, unfractionated heparin or fondaparinux

Question 21

Describe the repercussion flow diagram for a patient with a STEMI

Answer 21

Hospital provide PPCI - immediate PPCI

No PPCI available within acceptable time frame –> fibrinolysis

Fibrinolysis fail –> transfer to PCI hospital
Fibrinolysis successful –> angiography ± PCI during same admission

Question 22

What are the absolute contraindications for fibrinolytic therapy?

Answer 22

1. Previous haemorrhagic stroke
2. Ischaemic stroke during last 6 months
3. CNS damage/neoplasm
4. Recent major surgery, trauma or head injury (<3wk)
5. Active internal bleeding (not menses)
6. GI bleed within past month
7. Known/suspected aortic dissection
8. Known bleeding disorder

Question 23

What are the relative contraindications for fibrinolytic therapy?

Answer 23

1. Refractory HTN >180 mmHg
2. TIA <6months
3. Oral anticoagulant Rx
4. Pregnancy or <1wk post partum
5. Traumatic CPR
6. Non-compressible vascular puncture
7. Active PUD
8. Advanced liver disease
9. Infective endocarditis
10. Previous allergic reaction to fibrinolytic drug

Question 24

What may suggest that fibrinolytic therapy has failed?

Answer 24

1. Record ECG 60-90mins post.
2. Failure for ST elevation to resolve by >50% compared to pre-treatment

Question 25

How are patients with a non ST elevated ACS treated to prevent thrombus formation?

Answer 25

- SC **LMWH therapeutic dose 12hr** or Fondaparinux OD - **Aspirin 300mg** loading then **75mg daily** If NSTEMI or planned for angiography ± revascularisation - **Clopidogrel 300mg** (or 600mg loading) then **75mg daily** - **Prasugrel 60mg** then **10mg daily ** - **Ticagrelor 180mg** then **90mg BD** Can consider **glycoprotein IIb/IIIa inhibitor**

Question 26

How are patients with a non ST elevated ACS treated to reduce myocardial O2 demand?

Answer 26

1. **Beta blockers** - diltiazem if BB CI 2. **Avoid DHAP** Ca2+ blockers 3. **IV nitrate infusion** if angina persist 4. Consider **ACE inhibitor** - LV impairment or heart failure 5. **Rx Cx**

Question 27

How quickly should a patient with an NSTEMI have coronary angiography?

Answer 27

**Within 72h** of presentation

Question 28

Which ventricular arrhythmia's can complicate ACS?

Answer 28

1. Cardiac arrest with **VF or pVT** - presentation: 2. If VF/pVT occur **within 48h** of STEMI & **recovery uncomplicated** - risk of **recurrence low** 3. VF/pVT in context of **Non ST elevated ACS** - **risk** of **further** ventricular arrhythmia 4. If ventricular arrhythmia **late complication** - see by rhythm specialist for **ICD** implantation

Question 29

Which other arrhythmia's may occur in context of ACS?

Answer 29

AF - indicate left ventricular failure | AV block - inferior AMI

Question 30

How should AV block in context of ACS be managed?

Answer 30

1. Treat bradycardia with **atropine** 2. Consider **temporary pacing** if this fails 3. **PCI** typically resolve heart block

Question 31

What are the complications of ACS?

Answer 31

1. **Arrhythmia** 2. **HF** 3. **Cardiogenic Shock** ## Footnote Sudden Cardiac Death

Question 32

How can cardiogenic shock due to ACS be managed?

Answer 32

1. **Inotropic** therapy - adrenaline 2. **Intra-aortic balloon** pumping 3. Mechanical **circulatory/ventilatory** support

Question 33

What are some other causes of sudden cardiac death and how do they cause cardiac arrest? | Long + Short, AABCD - HH - W

Answer 33

1. Long QT - **Torsades**, VT, VF 2. Short QT - **Torsades**, VT, VF 3. Aortic stenosis - **HF**, VT, VF 4. Arrhythmogenic RV cardiomyopathy - VT, VF 5. Brugada 6. Catecholaminergic polymorphic VT - Torsades 7. Dilated cardiomyopathy - VT, VF 8. HOCM - VT, VF 9. High grade AV block - asystole (can **Torsades**/VT/VF) 10. WPW - AF transmit to ventricles - VT, VF