acute myocardial infarction

Question 1

what is the diagnostic criteria for a myocardial infarction?

Answer 1

• Rise and/or fall of troponin with at least one value >99th percentile of the URL, plus at least one of the following:
o Symptoms of ischaemia
o New ST segment or T wave changes or new left bundle branch block on ECG
o Development of pathological Q waves on ECG
o Imaging evidence of new loss of viable myocardium or new regional wall motion abnormality
o Identification of an intracoronary thrombus by angiographY

Question 2

why is troponin used as an indicator for cardiac damage?

Answer 2

its only found in cardiac myocytes

Question 3

what is a STEMI?

Answer 3

ST-elevation myocardial infarction

caused by ruptured coronary plaque with occlusive thrombus

Question 4

what does an ECG of an inferior STEMI show?

Answer 4

shows ST elevation in leads 2,3 and aVF

Question 5

what causes a NSTEMI?

Answer 5

caused by ruptured coronary plaque with sub-occlusive thrombus

Question 6

why is an ECG a non-diagnostic test for an NSTEMI?

Answer 6

Bc it doesn’t occlude the artery there are no ECG changes (no ST elevation) - ECG = non-diagnostic test

Question 7

why may a patient have stickier blood than another?

Answer 7

bc of smoking

Question 8

what effect does aspirin have on coagulability of the bood?

Answer 8

decreases coagulability

Question 9

what is a type 1 AMI and what causes it?

Answer 9

spontaneous AMI

plaque rupture

Question 10

what is a type 2 AMI and what causes it?

Answer 10

ischaemic imbalance

caused by coronary spasm, embolism, dissection, hypotension

Question 11

what is a type 3 AMI and what causes it?

Answer 11

cardiac death

presumed AMI

Question 12

what is a type 4a AMI and what causes it?

Answer 12

related to PCI

> 5 times URL for troponin

Question 13

what causes type 4b AMI and how is it diagnosed?

Answer 13

caused by stent thrombosis

confirmed at angiography or autopsy

Question 14

what is type 5 AMI?

Answer 14

related to CABG

>10 times URL for troponin

Question 15

what are the consequences of AMI-injury?

Answer 15

• Regional LV wall-motion abnormality

* The part of the heart that’s supplied by the blocked artery stops contracting

Question 16

how are the problems caused by coronary artery disease and cardiomyopathies different?

Answer 16

• Coronary artery disease causes local problems

* Cardiomyopathies causes global issues

Question 17

what are the clinical manifestations of ischaemic myocardial injury?

Answer 17

chest pain, 4th heart sound, low grade fever, leucocytosis and raised inflammatory markers (ESR, CRP)

Question 18

what are the clinical manifestations of autonomic disturbance?

Answer 18

tachycardia, sweating, vomiting

Question 19

what % of people with AMI die before they reach hospital?

Answer 19

33%

Question 20

what people is delay in calling for help characteristic of?

Answer 20

old people, women, nocturnal or w/e pain, no previous AMI, diabetics

Question 21

why do people with AMI die before getting to hospital?

Answer 21

ventricular fibrillation

Question 22

what determines whether or not you get pulmonary oedema with your AMI?

Answer 22

Extent of damage to the LV determines whether or not you get pulmonary oedema. A large occlusion = more damage

Question 23

how do you reduce mortality from AMI in hospitals?

Answer 23

reduce the size of the infarct

Question 24

what causes infarcts?

Answer 24

coronary thrombus

Question 25

how should infarcts be treated?

Answer 25

• Clot-busting drugs should be used e.g. streptokinase to dissolve the thrombus and restore flow to the heart muscle

Question 26

how are STEMIs treated?

Answer 26

First get them into theatre so they can have their arteries unblocked with balloons and stents
• Also flooded with anti-thrombotic drugs;
o Aspirin + ticagrelor
o Heparin
o PPCI

Question 27

name the antithrombotic drugs used in STEMI

Answer 27

Aspirin + ticagrelor
o Heparin
o PPCI

Question 28

how are NSTEMI patients treated?

Answer 28

• NSTEMI patients don’t need to be taken to theatre straight away – can be delayed for a few hours
• Meanwhile, give them drugs to stop partial occlusion progressing to a total occlusion
o Aspirin and ticagrelor
o ± GP IIb/IIIa inhibitor
o Fondaparinux (factor Xa inhibitor)
o Anti-ischaemic drugs (BB, nitrates)
o Angiography ± PCI within 24-96 hrs

Question 29

what prevention methods are there for saving lives post-hospital discharge?

Answer 29

• Lifestyle; smoking, diet, exercise
• Prevention drugs; aspirin, ticagrelor/prasugrel, statin, beta-blocker, ACE-I
• Prevention devices; ICD

Question 30

how long does treatment last for AMI patients?

Answer 30

• Treatment is for life except for ticagrelor/prasugrel

Question 31

by what % does quitting smoking affect your risk of a second AMI?

Answer 31

reduces risk by 40%

Question 32

what % of patients with AMI are current smokers?

Answer 32

20%

Question 33

how do you prevent pre-hospital death from primary VF?

Answer 33

get patient to a defibrillator ASAP

Question 34

how do you prevent hospital death from heart failure?

Answer 34

initiate reperfusion therapy ASAP

Question 35

how do you prevent late deaths?

Answer 35

a. Recurrent ischaemic events  secondary prevention therapy

b. Lethal arrhythmias  implantable defibrillator