Ischaemic heart disease Flashcards
Define angina pectoris
Symptomatic reversible myocardial ischaemia
Features of angina pectoris
- Constricting/heavy discomfort to the chest, jaw, neck, shoulders, or arms
- Symptoms brought on by exertion
- Symptoms relieved within 5 minutes by rest or GTN
All features = typical angina; 2 features = atypical angina, 0-1 features = non-anginal chest pain
Precipitates of angina
- Exertion
- Emotion
- Cold weather
- Heavy meals
Symptoms associated with angina (other than chest discomfort)
- Dyspnoea
- Nausea
- Sweatiness
- Faintness
Pathophysiology of stable angina
- Coronary artery narrowing by an atherosclerotic plaque reduces blood flow and oxygen delivery to the myocardium
- The atheroma also causes endothelial dysfunction, reducing vasodilator release (eg nitric oxide and prostacyclin)
- The demand for increased myocardial oxygen supply (eg by walking uphill) is unable to be met due to the stenosic lesion, resulting in myocardial ischaemia
- Ischaemia causes acidosis, decreased ATP production and release of lactate and other chemokines, which stimulate nerve cells in myocytes, producing the sensation of pain
Risk factors for angina
- Men affected twice as much as women
- South Asians more likely to be affected
- Modifiable risk factors:
- diabetes mellitus
- hypertension
- hyperlipidaemia
- smoking
- obesity
Investigations for angina
- Obtain and ECG
- Blood tests - FBC, U&Es, LFTs (required for statin therapy), glucose, HbA1c, cholesterol, HDL, LDL and triglycerides
- Consider echo and chest X-ray
Management of stable angina
- Optimise diet and lifestyle
- Prescribe aspirin and a statin
- Pharmacological therapy (GTN, beta blocker, calcium channel blocker)
Pharmacological therapy in stable angina
- Glyceryl trinitrate (GTN) should be used as and when necessary, repeating a second time after 5 minutes if the pain persists; call an ambulance if the pain persists 5 minutes after a second dose
- First line: beta blocker or calcium channel blocker (rate limiting eg verapamil)
- Increase the dose of monotherapy if still symptomatic
- Second line: beta-blocker and calcium channel blocker combination therapy (use a non-rate limiting agent, eg nifedipine)
How would you institute lipid modification therapy?
- Which blood tests would you require?
- What liver values would indicate it is safe to start statins?
- When should LFTs be measured after commencing statins?
- Which values give the best prediction of CVD risk? What is the role of LDL?
- What dose and which statin would you prescribe?
- Measuere a full lipid profile, including total cholesterol, HDL, LDL, triglycerides and liver function tests
- Statins are safe to start as long as liver transaminase results are less than 3 times the upper limit of normal
- LFTs should be measured within 3 months of starting treatment and at 12 months
- Ratio of total cholesterol to HDL cholesterol is the best predictor of CVD risk, while LDL cholesterol helps guide goals of lipid therapy
- Atorvastatin 20 mg for primary prevention if 10 year cardiovascular risk is >10%; atorvastatin 80mg for secondary prevention in patinets with pre-existing CVD
Indications for coronary artery bypass grafting in angina:
- Significant left main disease
- Three vessel disease
- Two vessel disease in diabetics
What are the criteria for metabolic syndrome?
How does this syndrome affect risk of cardioembolic events?
Metabolic syndrome is characterised by having 3 of the following 5 criteria:
- Hyperinsulinaemia (elevated fasting plasma glucose)
- Decreased HDL
- Central obesity
- Hypertriglyceridaemia
- Hypertension (>130/85)
This syndrome confers a threefold increase in the risk of cardioembolic event
Define acute coronary syndrome
ACS refers to a group of conditions that result from a sudden and unpredictable disruption in coronary blood flow. This includes unstable angina and myocardial infarction.
Clinical features of ACS
- Chest pain which is acute, central, crushing and retrosternal in nature, with or without radiation to the jaw, neck or arm
- Other symptoms include shortness of breath, sweating, nausea and vomiting
Risk factors for ACS
Non modifiable:
- Male sex
- South Asian ethnicity
- Age
- Familiy history of cardiovascular disease (<55 in men, <65 in women) in a first degree relative
- Dyslipidaemia
Modifiable:
- Diabetes mellitus
- Hypertension
- Hyperlipidaemia
- Smoking
- Obesity and sedentary lifestyle