acute myocardial infarction Flashcards
what is the diagnostic criteria for a myocardial infarction?
• 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
why is troponin used as an indicator for cardiac damage?
its only found in cardiac myocytes
what is a STEMI?
ST-elevation myocardial infarction
caused by ruptured coronary plaque with occlusive thrombus
what does an ECG of an inferior STEMI show?
shows ST elevation in leads 2,3 and aVF
what causes a NSTEMI?
caused by ruptured coronary plaque with sub-occlusive thrombus
why is an ECG a non-diagnostic test for an NSTEMI?
Bc it doesn’t occlude the artery there are no ECG changes (no ST elevation) - ECG = non-diagnostic test
why may a patient have stickier blood than another?
bc of smoking
what effect does aspirin have on coagulability of the bood?
decreases coagulability
what is a type 1 AMI and what causes it?
spontaneous AMI
plaque rupture
what is a type 2 AMI and what causes it?
ischaemic imbalance
caused by coronary spasm, embolism, dissection, hypotension
what is a type 3 AMI and what causes it?
cardiac death
presumed AMI
what is a type 4a AMI and what causes it?
related to PCI
> 5 times URL for troponin
what causes type 4b AMI and how is it diagnosed?
caused by stent thrombosis
confirmed at angiography or autopsy
what is type 5 AMI?
related to CABG
>10 times URL for troponin
what are the consequences of AMI-injury?
- Regional LV wall-motion abnormality
* The part of the heart that’s supplied by the blocked artery stops contracting
how are the problems caused by coronary artery disease and cardiomyopathies different?
- Coronary artery disease causes local problems
* Cardiomyopathies causes global issues
what are the clinical manifestations of ischaemic myocardial injury?
chest pain, 4th heart sound, low grade fever, leucocytosis and raised inflammatory markers (ESR, CRP)
what are the clinical manifestations of autonomic disturbance?
tachycardia, sweating, vomiting
what % of people with AMI die before they reach hospital?
33%
what people is delay in calling for help characteristic of?
old people, women, nocturnal or w/e pain, no previous AMI, diabetics
why do people with AMI die before getting to hospital?
ventricular fibrillation
what determines whether or not you get pulmonary oedema with your AMI?
Extent of damage to the LV determines whether or not you get pulmonary oedema. A large occlusion = more damage
how do you reduce mortality from AMI in hospitals?
reduce the size of the infarct
what causes infarcts?
coronary thrombus
how should infarcts be treated?
• Clot-busting drugs should be used e.g. streptokinase to dissolve the thrombus and restore flow to the heart muscle
how are STEMIs treated?
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
name the antithrombotic drugs used in STEMI
Aspirin + ticagrelor
o Heparin
o PPCI
how are NSTEMI patients treated?
• 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
what prevention methods are there for saving lives post-hospital discharge?
- Lifestyle; smoking, diet, exercise
- Prevention drugs; aspirin, ticagrelor/prasugrel, statin, beta-blocker, ACE-I
- Prevention devices; ICD
how long does treatment last for AMI patients?
• Treatment is for life except for ticagrelor/prasugrel
by what % does quitting smoking affect your risk of a second AMI?
reduces risk by 40%
what % of patients with AMI are current smokers?
20%
how do you prevent pre-hospital death from primary VF?
get patient to a defibrillator ASAP
how do you prevent hospital death from heart failure?
initiate reperfusion therapy ASAP
how do you prevent late deaths?
a. Recurrent ischaemic events secondary prevention therapy
b. Lethal arrhythmias implantable defibrillator
