acute coronary syndrome Flashcards
define acute coronary syndrome
a subclassification of ischemic heart disease which consists of the conditions:
- unstable angina
- non-ST elevation myocardial infarction (NSTEMI)
- ST-elevation myocardial infarction (STEMI)
most common cause of acute coronary syndrome
- rupture of atherosclerotic plaque resulting in thrombus formation in artery
what is the rate of artery occlusion in each of the conditions?
unstable angina and NSTEMI - partial occlusion
STEMI - complete occlusion because of thrombus
which conditions lead to myocardial necrosis?
STEMI and NSTEMI
presentation - the big 5
Smoking
Hypertension
Diabetes mellitus
Hypercholesterolaemia
Family history
signs and symptoms
Crushing/pressure-like chest pain that can radiate to the jaw/left arm
Typical symptoms due to reduced CO:
- Breathlessness
- Dizziness
- Weakness
Bilateral leg oedema may present if congestive heart failure (CHF) develops
STEMI investigations
ECG – differentiates between NSTEMI and STEMI
Biomarkers of myocyte necrosis
- Troponin T and I
- CK-MB
- Lactate dehydrogenase (outdated due to troponin testing)
modifiable risk factors (7)
Hypertension
Hyperglycaemia (DM)
Smoking
Alcohol
Hypercholesterolaemia
Obesity/inactivity
Stress
non-modifiable risk factors
Age
Sex (men and post-menopausal women)
Genetic/Family History
differentiation on ECG
STEMI - ST elevation
NSTEMI and UA - ST not elevated
if someone came in and had ecg showing st long segment what would you do?
automatically make a diagnosis of myocardial infarction and give MONA medication then organise PCI to revascularise the occlusion
differentiation on troponin level
UA - no raised troponin
NSTEMI and STEMI - do have raised troponin
primary prevention (before ACS has developed)
- Lifestyle advice (e.g. exercise, stop smoking, reduce alcohol, fats and salt, eat more fruit & veg)
- QRISK score
If above 10%, consider statins - ACE inhibitor if hypertensive
secondary prevention - after a patient has developed ACS
mnemonic - ABAS
- aspirin + antiplatelet 12 months
- Beta-blocker
- ACE inhibitor
- Statin
immediate management for acute presentation MI
mnemonic - MONA(C)
- Morphine IV
- Oxygen if low
- Nitrates
- Aspirin 300mg loading dose
- 2nd antiplatelet drug eg - (C)lopidogrel (ONLY IN STEMI)
PCI
NSTEMI
MONA
coronary angiogram either urgently or later, depending on risk
STEMI treatment <2hrs MI
percutaneous coronary intervention:
- balloon angioplasty or stenting
IF NOT
thrombolytic therapy
- Promotes plasminogen conversion to plasmin to break down fibrin clots
- First line is Tissue Plasminogen Activator (TPAs)
- Streptokinase is alternative
NSTEMI treatment <2hrs MI
- PCI
- thrombolytic therapy not inducated
criteria for PPCI for STEMI
ST elevation >2mm in 2 contiguous chest leads or >1mm in 2 contiguous limb leads (ie. territorial)
~Chest pain or other evidence of ischaemia
how aspirin works
blocks COX1 in low doses which inhibits thromboxine A2 - inhibits vasoconstriction
blocks COX2 - acts as an antiinflammatory
clopidogrel
P2Y12 inhibitor
prevents clotting
pro-drug
P2Y12 inhibitors
clopidogrel - pro-drug
prasugrel - not a pro-drug
why are PY12 inhibitors given
to prevent clotting - blood thinners
drugs - if patients develop complications from MI - for heart failure
milterocorticoid receptor antagonists
implantable cardioverter defibrillator - special pacemaker
Complications of MI
- Arrhythmia
- LV failure – pulmonary oedema, cardiogenic shock
Acute MI - Definition / diagnosis
Consistent clinical setting for myocardial necrosis PLUS
Rise and/or fall in cardiac biomarkers with at least one value >upper reference limit PLUS at least one of:
Symptoms of ischaemia
New/presumed new ST/T changes or LBBB
Development of pathological Q waves
Imaging (eg. echo, MR, LV gram) shows new loss of viable myocardium/RWMA
Intracoronary thrombus on angiography or autopsy
Type 1 MI = Spontaneous plaque rupture, ulceration, erosion, fissure, dissection with intraluminal thrombus
unstable angina
- considered to be present in patients with ischaemic symptoms suggestive of an ACS and no elevation in troponins, with or without electrocardiogram changes indicative of ischaemia
- however, as a rise in troponins may take some hours it may be indistinguishable for NSTEMI initially and is therefore treated the same until the troponin result is known
A 60-year-old man presents with acute chest pain and dizziness. His ECG shows ST elevation in leads II, III, and aVF, and ST depression in leads I and aVL.
Which of the following best explains the occurrence of reciprocal ST depression in leads opposite to the infarcted area?
electrical acitivity moving away from the infercted area produces reciprocal changes in opposit leads
Why is dual antiplatelet therapy (DAPT) recommended in the management of acute coronary syndromes (ACS), including STEMI?
using 2 antiplatelet drugs such as clopidogrel and aspirin to prevent further clotting in the coronary arteries
What is the role of beta-blockers in the acute management of STEMI?
- block the beta-adrenergic receptors in the heart
- prevents effects of sympathetic stimulation
- involves release of norepinephrine
leads to:
- red HR
- red myocardial contractility
- dec BP
How does the presence of ST-segment elevation in STEMI affect the urgency of treatment compared to NSTEMI?
ST elevation in STEMI - complete occlusion - full-thickness (transmural) myocardial infarction.
NSTEMI - blockage is partial - not full thickness
What is the role of angiotensin-converting enzyme (ACE) inhibitors in the management of STEMI?
prevent angiotensin I - angiotensin II
effects:
- vasodilation - reducing afterload
- red fluid retention - low BV - reduce oedema
What is the role of statins in the management of STEMI?
HMG-CoA reductase inhibitors:
(responsible for cholesterol synthesis)
- lowering cholesterol levels
- anti-inflammatory effects
- improve endothelial function
- slows progression of atherosclerosis
What is the role of morphine in the acute management of STEMI? (3)
- pain relief
- decreased sympathetic response
- vasodilation
which parts of an ECG correlate with which coronary arteries?
V1-V4 - left anterior descending
II, III, aVF - right coronary
I, V5-6 - left circumflex
