Coronary Artery Disease Flashcards
Coronary artery disease is characterised by:
The accumulation of atherosclerotic plaques within the coronary arteries.
Risk factors for CAD
- Family history of atherosclerosis
- Smoking
- Diabetes mellitus
- Hypertension
- Hyperlipidaemia
- Sedentary lifestyle
- Obesity
Describe typical angina
A constricting pain, tightness or discomfort in the front of the chest, and/or in the neck, shoulders, jaw or arms that is provoked by physical exertion and relieved by rest.
Unstable angina is defined by one or more of the following:
- Angina on exertion, occuring with increasing frequency over a few days, provoked by progressively less exertion. This is sometimes referred to as cresendo angina.
- Episodes of angina-like pain occuring recurently and unpredictably, without specific provocation by exercise.
- An unprovokekd and prolonged episode of chest pain raising suspicion of AMI but without definite ECG changes or laboratory evidence of AMI.
In unstable angina, the ECG may:
- Be normal
- Show evidence of acute myocardiac ischaemia (usually ST-segment depression)
- Show non-specific abnormalities (eg. T-wave inversion)
All patients with unstable angina should have their risk assessed using as established calculator, such as:
GRACE score (Global Registry of Acute Coronary Events)
Associated symptoms of MI
Nausea and vomiting, sweating, shortness of breath
Diagnosis of STEMI is based on:
- Sustained acute chest pain typical of AMI
- accompainied by acute ST elevation or new left bundle branch block on a 12 lead ECG
- St elevation >0.2mV in 2 adjacent chest leads OR
- > 0.1mV in 2 or more ‘adjacent’ limb leads OR
- Dominant R waves and ST depression in V1-V3 (posterior infarction) OR
- New onset (or presumed new onset) LBBB
Which groups of people are more likely to develop an ACS with little or no chest discomfort?
- Elderly people
- Diabetics
- Females
- People with renal disease
- People during a peri-oeprative period
Treatment for STEMI
This diagnosis mandates immediate treatment to re-open the occluded coronary artery (reperfusion therapy), preferably by emergency primary percutaneous coronary intervention. If this cannot be achieved within 120 minutes of the onset of chest pain, fibrinolytic therapy should be considered as an alternative. Therapy should not be delayed while awaiting troponin result.
Type of MI and artery affected if ECG changes in leads V1-V4:
(and if extension to involve V5-V6 and aVL)
Anterior MI
Left anterior descending (LAD) coronary artery
If extension to V5-V6 and aVL then anteriolateral MI
Type of MI and artery affected if ECG changes in leads II, III and aVF
Inferior infarction
Usually caused by lesion in the right coronary artery or, less commonly, the circumflex artery
Type of MI and artery affected if ECG changes in leads V5-V6 and/or leads I and aVL:
Lateral infarction
Usually caused by lesion in the circumflex artery or diagonal branch of the LAD artery
How can a posterior MI be recognised? Which artery is responsible? How can this diagnosis be confirmed?
Reciprocal ST segment depression in the anterior chest leads may indicate posterior myocardial infarction.
Most commonly caused by right coronary artery occlusion but may be caused by dominant circumflex artery lesion in some individuals.
Suspicion of posterior infarction can be confirmed by repeating the ECG using posterior leads.
In addition to aspirin, all patients should also be given one of the platelet ADP receptor blockers prior to PPCI, using one of the following loading doses:
- Clopidogrel 600mg
- Prasugrel 60mg (not if >75 years, <60kg, history of bleeding or stroke)
- Ticagrelor 180mg
