What is Acute coronory syndome(ACS)?

A collection of conditions resulting from occlusion of a coronary artery. (STEMI, NSTEMI, Unstable angina)

What causes ST-Elevation myocardial infarction (STEMI)?

Complete occultion of one of the coronary vessels leading to myocardial ischemia

Physiologically whats the difference between STEMI and NSETMI/unstable angina?

STEMI involves complete occlusion of a coronary vessel, NSTEMI/unstable angina involves a partial/intermittent occlusion

Physiologically what's the difference between NSTEMI and unstable angina?

NSTEMI involves myocardial ischemia and tissue damage, but unstable angina doesn't

What are the risk factors for Acute coronary syndrome (ACS)?

{{c1::

• Increasing age
• Male gender
• Family history::Unmodifiable}}

{{c2::

• Smoking
• Obesity::lifestyle}}

{{c3::

• Diabetes mellitus
• Hypertension
• Hypercholesterolaemia::diseases}}

What are the minimum criteria for STEMI?

Clinical symptoms of ACS for over 20 minutes with persistent ECG changes (>20 mins) in 2 or more contiguous leads

In what leads would you see changes in Anterior MI?

V1-V4 Left anterior descending

In what leads would you see changes in Inferior MI?

II, III, aVF - Right coronary

In what leads would you see changes in Lateral MI?

I, V5-6 Left circumflex

• STEMI criteria:
• {{c1::2.5 mm (i.e ≥ 2.5 small squares)}} ST elevation in leads V2-3 in men under 40 years, or {{c2::≥ 2.0 mm (i.e ≥ 2 small squares)}} ST elevation in leads V2-3 in men over 40 years
• {{c3::1.5 mm ST elevation}} in V2-3 in women
• {{c4::1 mm ST elevation}} in other leads
• {{c5::new LBBB (LBBB should be considered new unless there is evidence otherwise)::other change}}

What is a type 1 MI?

Caused typically by plaque rupture or erosion in a coronary artery causing a blood clot and reduced blood supply to heart tissue

What is a type 2 MI?

Caused by imbalance of myocardial oxygen supply and demand

What is a type 3 MI?

An MI resulting in death where biomarkers are unavailable

Acute coronary syndrome generally develops in patients with what underlying disease?

ischaemic heart disease

What is Ischeamic heart disease?

the gradually build up of fatty plaques within the walls of the coronary arteries.

Pathology of Atherosclerosis

• initial endothelial dysfunction is triggered by a number of factors such as {{c1::smoking, hypertension and hyperglycaemia}}
• this results in a number of changes to the endothelium including {{c2::pro-inflammatory, pro-oxidant, proliferative and reduced nitric oxide bioavailability}}
• fatty infiltration of the subendothelial space by {{c3::low-density lipoprotein (LDL) particles}}
• monocytes migrate from the blood and differentiate into macrophages. These macrophages then {{c4::phagocytose oxidized LDL, slowly turning into large 'foam cells'. As these macrophages die the result can further propagate the inflammatory process.}}
• {{c5::smooth muscle proliferation and migration from the tunica media into the intima}} results in formation of a fibrous capsule covering the fatty plaque.

What are the features of ACS chest pain?

• typically central/left-sided
• may radiate to the jaw or the left arm
• often described as 'heavy' or constricting, 'like an elephant on my chest'
• it should be noted however in real clinical practice patients present with a wide variety of types of chest pain and patients/doctors may confuse ischaemic pain for other causes such as dyspepsia
• certain patients e.g. diabetics/elderly may not experience any chest pain

What are the associated symptoms with ACS?

• dyspnoea
• sweating
• nausea and vomiting

Whats the Initial drug therapy for all patients with ACS?

• aspirin 300mg
• oxygen should only be given if the patient has oxygen saturations < 94% in keeping with British Thoracic Society oxygen therapy guidelines
• morphine should only be given for patients with severe pain
• nitrates - can be given either sublingually or intravenously

Whats the criteria for PCI in patients with STEMI?

• if the presentation is within 12 hours of the onset of symptoms
• AND PCI can be delivered within 120 minutes of the time when fibrinolysis could have been given
• OR if patients present after 12 hours and still have evidence of ongoing ischaemia then PCI should still be considered

When is fibrinolysis used in STEMI?

should be offered within 12 hours of the onset of symptoms if primary PCI cannot be delivered within 120 minutes of the time when fibrinolysis could have been given

IN ACS which second antiplatelet should be used prior to PCI if the patient is not taking an oral anticoagulant?

prasugrel

IN ACS which second antiplatelet should be used prior to PCI if the patient is taking an oral anticoagulant?

clopidogrel

Following thrombolysis in STEMI:

An ECG should be repeated after 60-90 minutes to see if {{c1::the ECG changes have resolved}}. If patients have {{c2::persistent myocardial ischaemia}} following fibrinolysis then PCI should be considered.

How is treatment of NSTEMI decided?

by using GRACE score to risk stratify

Which patients with NSTEMI/unstable angina should have coronary angiography (with follow-on PCI if necessary)?

• immediate: {{c1::patient who are clinically unstable (e.g. hypotensive)}}
• within 72 hours: {{c2::patients with a GRACE score > 3% i.e. those at intermediate, high or highest risk}}
• coronary angiography should also be considered for patients if {{c3::ischaemia is subsequently experienced after admission}}