Unstable angina

Question 1

What is unstable angina?

Answer 1

Myocardial ischaemia at rest or on minimal exertion in the absence of acute cardiomyocyte injury/necrosis

Question 2

What are the causes/ risk factors for unstable angina?

Answer 2

1. Mostly due to atherosclerosis. 
2. Risk factors: 
   - Smoking 
   - Hypertension 
   - Family history 
   - Diabetes 
   - Hyperlipidaemia 
   - Obesity 
   - Advanced age 
   - Peripheral vascular disease

Question 3

What are the presenting symptoms of unstable angina?

Answer 3

• Chest pain - central (cardiac) 
• Marked sweating 
• Epigastric pain 
• Dyspnoea 
• Syncope 
• Back pain 

Question 4

What signs of unstable angina can be found on physical examination?

Answer 4

1. Chest pain - the classical presentation can be considered in terms of the SOCRATES mnemonic:
   - Site - Central/left sided
   - Onset - Often sudden
   - Character - Crushing (‘like someone is sitting on your chest’)
   - Radiation - Left arm, neck and jaw
   - Associated symptoms - Nausea, sweating, clamminess, shortness of breath, sometimes vomiting or syncope
   - Timing - Constant
   - Exacerbating/relieving factors - Worsened by exercise/exertion and may be improved by GTN
   - Severity - Often extremely severe
2. Atypical presentations may include:
   - Epigastric pain
   - No pain (more common in elderly and patients with diabetes):
   - Acute breathlessness
   - Palpitations
   - Acute confusion
   - Diabetic hyperglycaemic crises
   - Syncope

Question 5

What investigations are used to diagnose/ monitor unstable angina?

Answer 5

1. ECG → typically no changes
2. Troponin → not elevated

Question 6

How is unstable angina managed?

Answer 6

1. 1st Line → Aspirin 300mg (and conitnue indefinitely) **+ Fondaparinux (antithrombin - if no immediate PCI planned)
2. Calculate GRACE (estimated 6 month mortality)
   - Low Risk (6 month mortality ≤3%) **→ ticagrelor + aspirin
   - Intermediate/High Risk (6 month mortality >3%) → angiography with followup PCI if indicated. Give ticagrelor.

Question 7

What complications may arise following unstable angina?

Answer 7

congestive heart failure, ventricular arrhythmias, treatment complications = bleeding or thrombocytopenia 

Question 8

Describe the prognosis following unstable angina

Answer 8

Overall mortality for the non-ST-elevation acute coronary syndrome (NSTE-ACS) patient population is 4.8% over a 6-month period

Question 9

Describe the pathophysiology behind unstable angina

Answer 9

The biggest cause is atherosclerosis; plaques are deposited to the walls of arteries making blood flow more difficult. Rarer causes include coronary artery spasm.

The initiating lesion is a fissure in the vessel endothelial lining over an underlying cholesterol plaque, which results in a loss in integrity of the plaque cap = rupture. The fissure or plaque rupture leads to exposure of subendothelial matrix elements (such as collagen), stimulating platelet activation and thrombus formation. Release of tissue factor directly activates the coagulation cascade and promotes the formation of fibrin.

1. Endothelial injury leads to migration of monocytes into the subendothelial space
2. These monocytes differentiate into macrophages
3. Macrophages accumulate LDL lipids and become foam cells.
4. These foam cells release growth factors that stimulate smooth muscle proliferation, production of collagen and proteoglycans.
5. This leads to the formation of an atherosclerotic plaque – risk of rupture of plaque

Question 10

Describe the epidemiology behind unstable angina

Answer 10

3% of people