Myocardial infarction

Question 1

what is a myocardial infarction?

Answer 1

persistent blockage of coronary artery leading to necrosis

risk of dying from ventricular fibrillation is high

Question 2

What are the symptoms of myocardial infarction?

Answer 2

constricting chest pain, radiates to arms, neck and jaw
anxiety
sweating
nausea and vomiting

Question 3

What are the 3 cardiac enzymes elevated in the blood hours after an MI?

Answer 3

a peak in creatine kinase is followed by aspartate transaminase and then lactate dehydrogenase

Question 4

What are the indicators of myocardial necrosis?

Answer 4

Troponin T and Troponin I (muscle proteins)

Question 5

What is the diagnostic criteria for an MI?

Answer 5

rise and/or fall in troponin with at least one value > 99th percentile of the upper reference limit, plus at least one of the following:
symptoms of ischaemia e.g. chest pain
ECG changes
imaging evidence of new loss of viable myocardium or new regional wall motion abnormality

Question 6

What is the difference between a STEMI and a NSTEMI?

Answer 6

STEMI - fully occluded artery

NSTEMI - partially occluded artery

Question 7

What are the clinical manifestations of AMI?

Answer 7

Ischaemic myocardial injury:
chest pain
S4
low grade fever
raised inflammatory markers (ESR, CRP)
troponin leak

Question 8

What autonomic disturbances occur in an AMI?

Answer 8

tachycardia
sweating
vomiting

Question 9

What leads to mortality in AMI?

Answer 9

ventricular fibrillation causes death if not resuscitated

left ventricular failure: left sided heart failure and pulmonary oedema

Question 10

What are the early complications of MI?

Answer 10

arrhythmias
heart failure
pericarditis
myocardial rupture 
thromboembolism

Question 11

What are the late complications of AMI?

Answer 11

LV aneurysm
pericarditis
heart failure

Question 12

What are the other complications of AMI?

Answer 12

3rd AV block: atria and ventricles are completely separated and beat independently
Ventricular septal defect: blood passes from left ventricle to right ventricle during ventricular contraction
Papillary muscle rupture: valve doesn’t work leads to regurgitation into atria during contraction

Question 13

What are the life saving strategies in AMI?

Answer 13

1. prevent hospital death from primary ventricular fibrillation: get defibrillator ASAP
2. Prevent hospital death from heart failure: initiate reperfusion therapy ASAP
3. Prevent late deaths from: recurrent ischaemic events (secondary prevention therapy) and lethal arrythmias (implantable defribillator)

Question 14

Name the drugs or intervention used in STEMI repercussion therapy

Answer 14

Asprin + clopidogrel
tPA infusion or bolus tenecteplase
LMWH - fondaparinux (factor Xa inhibitor)
PCI
Secondary prevention drugs
Secondary prevention lifestyle

Question 15

Name the secondary prevention drugs

Answer 15

aspirin
clopidogrel
statin
beta blocker
ACE

Question 16

Name the secondary prevention lifestyle

Answer 16

smoking
diet
exercise

Question 17

What is the first step in STEMI treatment?

Answer 17

Go to Cath lab immediately for angiography/PCI

If LAD occlusion - PCI

Question 18

What drug should be given during a PPCI?

Answer 18

give GPIIa/IIIa inhibitors to reduce risk of immediate vascular occlusion

Question 19

When should surgical procedure be carried out in a NSTEMI patient to prevent future cardiovascular events?

Answer 19

immediate risk (3-6%)
high risk >6%

Question 20

Name the drugs or interventions used in the emergency treatment of NSTEMI

Answer 20

1. Anti platelets: Aspirin, clopidogrel +/- GP IIb/IIIa
2. LMWH - fondaparinux
3. anti-ischemic drugs - beta blockers, nitrates
4. +/- angioplasty, PCI
5. Secondary prevention drugs
6. Secondary prevention lifestyle

Question 21

What treatment is offered for low risk (<3%) NSTEMI patients to prevent future cardiovascular events?

Answer 21

Aspirin + Fondaparinux + Clopidogrel

Conservative Management

Question 22

When should NSTEMI patients be taken to the Cath lab?

Answer 22

24 - 96 hours later

Question 23

Which MI has a higher probability of dying days after presentation?

Answer 23

NSTEMI patients

Question 24

What is required to identify high risk patients?

Answer 24

tests that are readily available in hospitals that treat the bulk of patients
tests that can be performed sufficiently early after infarction to anticipate the period of greatest risk
tests with high sensitivity
tests with high +ve predictive accuracy
tests for which the therapeutic implications of an abnormal result are well defined

Question 25

What does an ECG tell us about an MI?

Answer 25

It shows an inferior infarction of the heart

Question 26

What is the mortality rate for patients with an MI?

Answer 26

30 day mortality

Question 27

Which patients are at most risk of an MI?

Answer 27

old age
diabetic
any degree of heart failure

Question 28

Which risk scoring system is used to identify individual risk of future adverse cardiovascular events?

Answer 28

Global Registry of Acute Cardiac (GRACE) risk score
The risk is defined as:
low: up to 3%
intermediate: 3-6%
high: greater than 6%
Risk can be assessed at admission or at discharge to 6 months

Question 29

When should an implantable defibrillator be used as secondary prevention for post AMI patients?

Answer 29

late cardiac arrest VT/VF
sustained ventricular tachycardia with syncope
sustained ventricular tachycardia and left ventricular ejection fraction <35%

Question 30

When should an implantable defibrillator be used as primary prevention for post AMI patients?

Answer 30

AMI > 4 weeks previously
LV ejection fraction 120ms
LV ejection fraction <35% and non sustained VT on Holter