Acute Coronary Syndrome (ACS) Flashcards
(27 cards)
What is ACS?
ACS refers to three states of myocardial ischaemia- unstable angina, non-ST elevation myocardial infarction, and ST elevation myocardial infarction. ACS is a medical emergency requiring urgent admission.
What is the most significant aetiological factor that causes ACS?
Atherosclerosis
What are the clinical features, ECG findings and cardiac enzymes found in the three classifications of ACS? (Very IMP)
1) STEMI- ST-segment elevation or new onset left bundle branch block, and raised troponin
2) NSTEMI- Other ischemic changes or normal ECG, and raised Troponin
3) Unstable angina- Characteristic clinical features, Other ischemic changes or normal ECG, and normal troponin.
What is an MI, and how do you diagnose it?
MI refers to the death of cardiac tissue- myocardial necrosis.
For its diagnosis, you require the detection of a cardiac biomarker (troponin), and at least one of the following:
- symptoms of MI (chest pain)
- new or presumed ECG changes (ST-T wave cahnges or new left bundle branch block)
- development of pathological Q waves
- imaging evidence of infarction (loss of viable myocardium or new motion abnormality
- angiography
What is ACS typically triggered by? Explain the pathophysiology behind it.
- Typically triggered by rupture of an atheromatous plaque in the coronary arterial wall. Atherosclerosis causes narrowing of the coronary vessels (this is known as CAD/IHD)
- CHD/IHD can lead to angina
- if atheromatous plaque ruptures, it leads to thrombus formation and acute occlusion that causes ACS
What are the risk factors for developing atherosclerosis? (divide it into modifiable and non-modifiable)
Modifiable:
- High cholesterol
- hypertension
- Smoking
- Diabetes
- Obesity
Non-modifiable:
- Age
- family History
- male sex
- premature menopause
What are some other causes of ACS?
1) emboli (valvular disease)
2) coronary dissection
3) oxygen supply/demand mismatch- there is not total occlusion, instead there is not enough blood being delivered through the coronary arteries to meet the demand of the cardiomyocytes, which leads to necrosis and troponin rise. Eg,- anemia, hyperthyroidism, severe sepsis.
4) vasculitis (Kawaski disease)
5) Coronary vasospasm (spontaneous, cocaine)
What is an MI vs a myocardial injury?
1) Myocardial infarction: myocardial necrosis, seen as a rise in troponin, with evidence of acute myocardial ischaemia
2) Myocardial injury: myocardial necrosis, seen as a rise in troponin, without evidence of acute myocardial ischaemia
What types can MI be divided into? (5 types)
Type 1: due to a primary coronary artery event such as plaque rupture and/or dissection
Type 2: due to an oxygen supply/demand mismatch
Type 3: sudden unexpected cardiac death presumed secondary to myocardial ischaemia
Type 4: associated with percutaneous coronary intervention or stent complications
Type 5: associated with cardiac surgery
What are some examples of myocardial injury?
- myocarditis
- damage following cardioversion/ablation
- cytokine-mediated injury
Explain the pathophysiology of Atherosclerosis.
Step 1: Endothelial injury- causes inflammatory response- leads to accumulation of LDLs- these become oxidised by local waste products creating ROS.
Step 2: Plaque formation- endothelial cells attract monocytes (macrophages)- these phagocytose the LDLs to become foam cells and fatty streaks
Step 3: Plaque rupture- continued inflammation triggers smooth muscle cell migration which forms a fibrous cap with the fatty streaks and develops into an atheroma- the top of the atheroma forms a hard plaque which may rupture- platelets aggregate on this exposed collagen forming a thrombus- or the thrombus could become an embolus and occlude the vessel.
What are the clinical symptoms and signs of an ACS?
Symptoms:
1) Chest pain > 15 minutes: central crushing or pressing pain +/- radiation to neck or arm or jaw
2) Shortness of breath
3) Sweating
4) Nausea and vomiting
5) Palpitations
Signs:
1) Pale
2) Clammy
3) Tachycardia
4) Cardiac failure (e.g. pulmonary oedema, hypotension)
What are some features of ACS on the ECG?
- ST elevation
- LBBB
Other ischemic changes:
- ST depression
- T wave inversion
What are some causes of ST elevation on an ECG?
- myocardial ischemia
- pericarditis
- coronary vasospasm
- benign early repolarization
- bundle branch block
- ventricular aneurysm
What are some causes of ST depression?
- acute myocardial ischemia
- reciprocal change to ST elevation
- electrolyte disturbances
- digoxin effect
- bundle branch block
What do T wave changes mean on an ECG?
- myocardial ischemia even in the absence of ST changes
What are some causes of Troponin Elevation?
- tachyarrhythmias
- heart failure
- hypertensive emergencies
- critical illness (sepsis, burns)
- myocarditis
- cardiomyopathy
- structural heart disease
- pulmonary embolism
- renal dysfunction
- coronary spasm
- acute neurological event
What are the investigations you would do in the case of an ACS?
- ECG
- BP
- Cap blood glucose
- Troponin levels
- FBC
- U&Es
- LFTs
- TFTs
- CRP
- Lipid profile
- coagulation
- group and save
- HbA1c
- Chest Xray
- Echo
- CT pulmonary angiography- if PE is suspected or needs to be ruled out
- CT angiography- if aortic dissection is suspected
What are the cardiac, respiratory, GI and other differential diagnoses of chest pain?
Cardiac:
- angina
- ACS
- pericarditis
- aortic dissection
Resp:
- PE
- Pneumothorax
- Pneumonia
GI:
- Esophagitis
- esophageal spasm
- peptic ulcer disease
Other:
- Rib fracture
- herpes zoster
- costochondritis
- depression/anxiety
What is the management of ACS?
MONA:
M- Morphine + anti-emetic
O- Oxygen
N- Nitrates (GTN- potent vasodilator)
A- Aspirin (300mg)
What are the treatments for a STEMI?
1) emergency coronary angiography+/- primary percutaneous coronary intervention.
2) Fibrinolysis (alteplase- if PCI cannot be performed within 120 mins)
3) Antiplatelets- aspirin
4) Anti-thrombotic agents (low molecular weight heparin, glycoprotein IIb/IIIa inhibitors)
How does emergency coronary angiography+/- primary percutaneous coronary intervention work?
Coronary angiography involves insertion of a catheter via the femoral artery or radial artery. From here, the catheter can be passed to the coronary artery vessels with x-rays for guidance and contrast injected. During the procedure a balloon catheter can be inserted to open up a blockage. A stent can be then be inserted into the blocked artery.
Note: This needs to be performed within 120 minutes of diagnosis.
What is the treatment for NSTEMI/UA?
BATMAN
B- Beta blockers
A- Aspirin (300mg, then 75mg daily)
T- Ticagrelor (180mg, and then 80mg daily) or clopidogrel if high bleeding risk
M- Morphine
A- antithrombotic agent (fondaparinux- 2.5 mg, eparin if patient planned for a coronary angiography within the next 24 hours)
N- nitrates (sublingual nitrates to relieve pain)
In which patient conditions (high risk) would a coronary angiography be appropriate immediately?
- cardiogenic shock (mechanical issue where the heart is unable to pump enough blood around the body)
- pain refractory to medical therapy
- life-threatening arrhythmia or cardiac arrest (electrical problem which haults the hearts function altogether)
- mechanical complication (valve rupture)
- acute HF with refractory angina
- Recurrent dynamic ECG changes
