Belongs to a group of acute coronary syndromes along with unstable Angina. These share a common pathology atherosclerotic plaque rupture, thrombosis and inflammation. However may also be rarely due to emboli, coronary spasm or vasculitis
Myocardial infarction - there is myocardial cell death → release of troponin Ischaemia - lack of blood supply (possible not cell death - no troponin in unstable angina)
Subendocardial myocardium is relatively poorly perfused under normal conditions. Given:
- stable atheromatous occlusion of the coronary circulation
- an acute hypotensive episode The subendocardial myocardium can infarct without any acute coronary occlusion (NSTEMI)
Causes/Factors
- Age
- Family history of Coronary Artery Disease
- Smoking
- Hypertension
- Familial hypercholesterolaemia
- Hyperlipidaemia
- Obesity
- Sedentary lifestyle
- Cocaine use
Symptoms
- Severe crushing central/generalised pain - sudden onset
- Often pain radiates out to left arm/neck
- Nausea
- Dyspnoea
- Palpitations
- Syncope
- Pulmonary oedema
Signs
- Distress
- Anxiety
- Vomiting
- Sweatiness
- Possible
Diagnostic Tests
| Artery | Heart Area | ECG Leads |
|---|---|---|
| Left coronary artery | Anterolateral | I, aVL, V3-6 |
| Left anterior descending | Anterior | V1-4 |
| Circumflex | Lateral | I, aVL, V5-6 |
| Right coronary artery | Inferior | II, III, aVF |
- ECG - ST elevation (STEMI), T-wave inversion, ST Depression (NSTEMI) - ECG Lead Placement & Interpretation
- Bloods - raised troponin, cardiac enzymes, creatine kinase for NSTEMI
- Echo to see area of reduced contraction
- Coronary angio to show which artery is blocked
Management
Acute:
MOAN pneumonic
-
Morphine 5-10mg (with Metoclopramide 10mg)
-
Aspirn 300mg + ticagrelor 180mg - dual anti-platelet therapy. Clopidogrel if high bleeding risk, or prasugrel if having angiography.
-
Nitrates - GNT spray
-
PCI must be within 2 hours otherwise thrombolysis
Antithrombin therapy in NSTEMI with fondaparinux
Unstable patients immediately get an angio otherwise for NSTEMI calculate GRACE score:
- 3% or less is considered low risk
- Above 3% is considered medium to high risk
Patients at medium or high risk are considered for early angiography with PCI (within 72 hours). Factors in GRACE score is age HR systolic BP and associated symptoms
Post MI 6A’s:
- Aspirin 75mg indefinitely
- Another Anti-platelet - ticagrelor or Clopidogrel for 12 months
- Atorvastatin 80mg once daily
- ACE inhibitor as high as tolerated
- Atenolol or another beta blocker
- Aldosterone antagonist in those with Heart Failure
Complications/red Flags
Dressler’s Syndrome
- 2-3 weeks after an MI
- Localised immune reponse that causes a pericarditits
- Pleuritic chest pain, low-grade fever and pericardial rub on auscultation
- Global ST elevation and TWI, pericardial effusion and raised CRP and ESR
- Management is with NSAIDs and in severe cases steroids ± pericardiocentesis
- Arrhythmias - most common complication
- Pericarditis
- Cardiac Tamponade
- LV/RV failure