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
Acute coronary syndrome immediate investigations
- Obtain ECG - compare with olde ECGs if possible
- Blood tests - Trooponin T or I (serial, 6 hours apart, looking for a peak in the measured values), FBC, U&Es, LFTs
- Chest X-ray
- assess cardiomediastinal contours (eg the presence of cardiomegaly, mediastinal widening in aortic dissection)
- lung fields (eg signs of heart failure)
- exculde non-cardiac causes of chest pain (eg pneumothorax, pneumonia)
Apart from myocardial infarction, which conditions can cause elevated troponin?
- Acute heart failure
- Myocarditis
- Pericarditis
- Pulmonary embolism
- Renal failure
- Sepsis
Initial management of acute coronary syndrome
- Continuous cardiac monitoring
- Administer aspirin 300mg, plus another antiplatelet agent (eg clopidogrel)
- Oxygen - only if SpO2 <94%
- GTN - avoided if systolic BP <90mmHg
- IV morphine for pain eg 2.5mg blouses, 5 minutes apart
- IV metoclopramide - ischaemia and morphine are both emetogenic
- Tight glucose control - glucose should be monitored regularly
Advanced management of STEMI
- Primary percutaneous coronary intervention (PPCI)
- Gold standard repercussion strategy in STEMI
- Indicated if symptoms onset occurd within 12 hours
- Procedure should be performed within 90-120 minutes of diagnosis
- Bivalirudin (direct thrombin inhibitor) in combination with aspirin and clopidogrel, is recommended for patients with STEMI undergoing PPCI
- Thombolysis
- Should only be performed if patients are unable to receive PCI within 90-120 minutes of diagnosis, or where PPCI is contraindicated
- ECG should be performed 90 minutes after thromolysis
- Look for 50% reduction in ST elevation
- If inadequate response, consider PCI within 6 hours of thombolysis
Features of STEMI on ECG
- ST elevation of ≥1mm in at least 2 adjacent limb leads or ≥2mm in contiguous precordial leads
- New onset of LBBB (less specific for STEMI)
How to establish diagnosis of NSTEMI or UA
- NSTEMI: positive troponin +- ischaemic changes on ECG (eg ST depression, T wave inversion)
- Unstable angina negative troponin +- ischaemic changes on ECG
Management of NSTEMI/UA
NICE recommends the GRACE score to predict 6 monthly mortality
- If low risk (predicted 6 month mortality <3%)
- Offer patients anticoagulation (fondaparinux 2.5mg SC is recommended for 8 days or until discharge) without early angiography and proceed to post acute management
- If intermittent (3-6%) or high risk (>6%)
- Offer IV glycoprotein IIb/IIIa inhibitors and anticoagulation (bivalirudin or unfractionated heparin recommended)
- Arrange coronary angiography within 96 hours of admission and consider PCI
Post acute management of acute coronary syndrome
-
Anitplatelet agents
- Aspirin 75mg lifelong following ACS
- P2-Y12 inhibitors eg clopidogrel for 12 months
- Statin therapy lowers mortality; atorvastatin 80mg
- Beta blockers lowers mortality and provides symptomatic relief
- Nitrates regular (if required) and PRN for all patients
- ACE inhibitors lowers mortality, and prevents ventricular remodelling and subsequent heart failure
Complications of acute coronary syndrome
Sudden death on PRAED street
- Sudden death
- Pump failure or Pericarditis
- Rupture (eg of LV free wall, septum or papillary muscle)
- Aneurysn or Arrhythmia
- Embolism
- Dressler syndrome
Right ventricular failure
- Associated with which type of MI?
- Suspect if:
- Treatment
- Why should nitrates and diuretics be avoided?
- Associated with inferior wall MI
- Suspect if clear lung fields, elevated JVP and systemic hypotension
- Fluid boluses that augment RV preload (eg 250ml 0.9% NaCl over 10 minutes)
- Nitrates and diuretics reduce preload, which will worsen the condition of right ventricular failure, as filling of the right side of the heart is already impaired