Chapter 4: Cardiac Causes of Cardiac Arrest

Question 1

How can acute coronary syndrome be split up?

Answer 1

ST elevated myocardial infarction

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

ST depression
Dynamic ECG changes (different from baseline)
Unstable rhythm
Unstable haemodynamics
Diabetes
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

Indigestion type pain
Pain radiate to throat, into one or both arms, into back or upper abdomen
Asymptomatic

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

VF
VT
Sudden death

Question 10

What ECG changes may be seen in a STEMI?

Answer 10

ST elevation
New LBBB
Pathological q waves
T wave inversion
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

Subarachnoid haemorrhage
Traumatic brain injury

Major PE - t wave inversion

Question 15

Why is echocardiography useful in acute ACS?

Answer 15

Confirm LV systolic function - related to prognosis

Can prompt diagnoses of cardiomyopathy, valve disease, pericardial disease, aortic dissection and PE

Can confirm RV dilatation and 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?

Answer 20

• Aspirin 300mg loading dose AND
• Clopidogrel 300mg loading dose AND
• 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

• Previous haemorrhage stroke
• Ischaemic stroke during last 6 months
• CNS damage/neoplasm
• Recent major surgery, trauma or head injury (<3wk)
• Active internal bleeding (not menses) OR GI bleed within past month
• Known/suspected aortic dissection
• Known bleeding disorder

Question 23

What are the relative contraindications for fibrinolytic therapy?

Answer 23

• Refractory HTN >180 mmHg
• TIA <6months
• Oral anticoagulant treatment
• Pregnancy or <1wk post partum
• Traumatic CPR
• Non-compressible vascular puncture
• Active peptic ulcer disease
• Advanced liver disease
• Infective endocarditis
• Previous allergic reaction to fibrinolytic drug

Question 24

What may suggest that fibrinolytic therapy has failed?

Answer 24

Record ECG 60-90mins post.

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

- Beta blockers - diltiazem if BB CI - Avoid DHAP Ca2+ blockers - IV nitrate infusion if angina persist - Consider ACE inhibitor - LV impairment or heart failure - Treat complications

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

Cardiac arrest with VF or pulseless VT - presentation If VF/pVT occur within 48h of STEMI and recovery uncomplicated - risk of recurrence low VF/pVT in context of Non ST elevated ACS - risk of further ventricular arrhythmia 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

Treat bradycardia with atropine Consider temporary pacing if this fails PCI typically resolve heart block

Question 31

What are the complications of ACS?

Answer 31

Arrhythmia Heart Failure Cardiogenic Shock

Question 32

How can cardiogenic shock due to ACS be managed?

Answer 32

Inotropic therapy - adrenaline Intra-aortic balloon pumping Mechanical circulatory/ventilatory support

Question 33

What are some other causes of sudden cardiac death and how do they cause cardiac arrest?

Answer 33

Long QT - Torsades, VT, VF Brugada Short QT - Torsades, VT, VF Catecholaminergic polymorphic VT - Torsades Arrhythmogenic RV cardiomyopathy - VT, VF HOCM - VT, VF WPW - AF transmit to ventricles - VT, VF High grade AV block - asystole (can Torsades/VT/VF) Aortic stenosis - HF, VT, VF Dilated cardiomyopathy - VT, VF