Ischaemic heart disease Flashcards by Clarissa Rowe

Define ischaemic heart disease

Characterised by decreased blood supply to the heart muscle resulting in chest pain (angina pectoris)

May present as stable angina or acute coronary syndrome

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Acute coronary syndrome subdivisions

Unstable angina - chest pain at rest due to ischaemia but without cardiac injury
NSTEMI
STEMI - ST elevation w/ transural infarction

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Define myocardial infarction

cardiac muscle necrosis resulting from ischaemia

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Aetiology of ischaemic heart disease

Angina pectoris occurs when myocardial oxygen demand exceeds oxygen supply

Usually due to atherosclerosis

Rare causes: coronary artery spasm (e.g. induced by cocaine), arteritis, emboli

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Pathophysiology of atherosclerosis

Endothelial injury —> migration of monocytes to sub endothelial space

Monocytes differentiate into macrophages which accumulate LDLs & become foam cells

Foam cells release growth factors that stimulate smooth muscle proliferation, production of collagen & proteoglycans —> formation of atherosclerotic plaque

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Risk factors for ischaemic heart disease

Male 
Diabetes mellitus 
FH
Hypertension
Hyperlipidaemia 
Smoking

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Epidemiology of ischaemic heart disease

prevalence x2, gender, incidence

COMMON
Prevalence >2%
More common in males
Annual incidence of MI un UK 5/1000

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Presenting symptoms of ischaemic heart disease - ACS

Acute onset chest pain
Central, heavy, tight, crushing pain
Radiates to arms, neck, jaw or epigastrium
Occurs at rest
More severe & frequent pain than previously occurring stable angina

Associated symptoms:
breathlessness
sweating
N&V
SILENT INFARCTS (elderly & diabetics)

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Presenting symptoms of ischaemic heart disease - stable angina

Chest pain brought on by exertion & relieved by rest

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Signs of ischaemic heart disease on physical examination - ACS
(10)

May be NO CLINICAL SIGNS
Pale 
Sweating
Restless
Low grade pyrexia
Check both radial pulses to rule out aortic dissection 
Arrhythmias
Disturbances of BP
New heart murmurs
Signs of complications (e.g. acute heart failure, cardiogenic shock)

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Signs of ischaemic heart disease on physical examination - stable angina

Check for signs of risk factors

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Investigations for ischaemic heart disease

9 groups

Bloods
ECG
CXR
Exercise ECG
Radionuclide myocardial perfusion imaging (rMPI)
Echocardiogram
Pharmacological stress testing
Cardiac catheterisation/angiography 
Coronary calcium scoring

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Investigations for ischaemic heart disease - bloods

FBC
U&Es
CRP
Glucose
Lipid profile 
Cardiac enzymes (troponin & CK-MB)
Amylase (pancreatitis can mimic MI)
TFTs
AST & LDH (raised 24 & 48 hrs post MI respectively)

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Investigations for ischaemic heart disease - ECG

1 unstable angina/NSTEMI + 4 STEMI

Unstable angina or STEMI
May show ST depression or T wave inversion

STEMI
Hyperacute T waves
ST elevation (> 1mm in limb leads, > 2mm in chest leads)
New onset LBBB
Later changes:
T wave inversion
pathological Q waves

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ECG leads & sides of the heart

Inferior - II, III, aVF
Anterior - V1-5/6
Lateral - I, aVF, V5/6
Posterior - tall R wave & ST depression in V1-3

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Investigations for ischaemic heart disease - CXR

Check for signs of heart failure

Investigations for ischaemic heart disease - exercise ECG

3 indications + 3 results

Indications
Patients w/ troponin negative ACS or stable angina w/ high pretest probability of coronary heart disease
Pretest probability based on characteristics:
chest pain, cardiac risk factors, age, gender
Digoxin associated w/ false positive result
(& β-blockers reduce HR so should be stopped before test)

Results
Positive test: > 1mm horizontal or downsloping ST depression measured 80ms after end of QR complex
Failed test: failure to achieve at least 85% of predicted maximal heart rate (220-age) & otherwise negative findings (no chest pain or ECG changes)
Resting ECG abnormalities: e.g. pre excitation syndrome, >1mm ST depression, LBBB or pacemaker ventricular rhythm

Investigations for ischaemic heart disease - radionuclide myocardial perfusion imaging
(3)

Uses technetium-99m sestamibi or tetrofosmin
Can be performed under stress or at rest
Stress testing shows low uptake in ischaemic myocardium

Investigations for ischaemic heart disease - echocardiogram

Measured left ventricular ejection fraction

Exercise or dobutamine stress echo may detect regional wall motion abnormalities

Investigations for ischaemic heart disease - pharmacological stress testing
(3)

Used in patients unable to exercise
Pharmacological agents used to induce tachycardia - e.g. dipyridamole, adenosine, dobutamine
Used in conjunction w/ various imaging modalities (e.g. rMPI, echocardiography) to detect ischaemic myocardium

Dipyridamole & adenosine contraindicated in AV block & reactive airway disease

Investigations for ischaemic heart disease - cardiac catheterisation/angiography

Performed if ACS w/ positive troponin or high risk on stress testing

Investigations for ischaemic heart disease - coronary calcium scoring
(2)

Uses specialised CT scan

May useful in outpatients w/ atypical chest pain or in acute chest pain that isn’t clearly due to ischaemia

Management of stable angina

Minimise cardiac risk factors
e.g. BP, hyperlipidaemia, diabetes
All patients should receive aspirin 75mg/day unless contraindicated

Immediate symptom relief
e.g. GTN spray

Long term management
β-blockers
Calcium channel blockers
Nitrates

Percutaneous coronary intervention (PCI)
Performed in patients w/ stable angina despite maximal tolerable medical therapy

Coronary artery bypass graft (CABG)
Occurs in more severe cases (e.g. three-vessel disease)

Β blockers contraindicated in…

acute heart failure
cardiogenic shock
bradycardia 
heart block
asthma

Management of unstable angina/NSTEMI | 12

Admit to coronary care unit Oxygen, IV access, monitor vital signs & serial ECG GTN Morphine Metoclopramide (to counteract morphine nausea) Aspirin (300mg initially, 75mg indefinitely) Clopidogrel (300mg initially, 75mg for at least 1 yr if troponin positive or high risk) LMWH (e.g. enoxaparin) β-blocker (e.g. metoprolol) Glucose-insulin infusion if blood glucose >11 mmol/L GIpIIb/IIIa inhibitors may also be considered (e.g. tirofiban) in patients: undergoing PCI at risk of further cardiac events If little improvement, consider urgent angiography with/without revascularisation

MONABASH pneumonic for...

Management of unstable angina/NSTEMI ``` Morphine Oxygen Nitrates Anticoagulants (aspirin + clopidogrel) β-blockers ACE inhibitors Statins Heparin ```

Management of STEMI | 7 groups

Same as UAP/NSTEMI management except: Clopidogrel Primary PCI Thrombolysis Secondary prevention Advice CABG

Management of STEMI - clopidogrel | 4

600mg if patient is going to PCI 300mg if undergoing thrombolysis & <75 yrs 75mg if undergoing thrombolysis & >75 yrs Maintenance 75mg daily for at least 1 yr

Management of STEMI - primary PCI | 3

IV heparin (plus GIpIIb/IIIa inhibitor) Bivalirudin (antithrombin) Goal <90 mins if available

Management of STEMI - thrombolysis | 3

Uses fibrinolytics such as streptokinase & tissue plasminogen activator (e.g. alteplase) Only considered within 12 hrs of chest pain & ECG changes & not contraindicated Rescue PCI may be performed if continued chest pain or ST elevation after thrombolysis

Management of STEMI - secondary prevention | 5

``` Dual antiplatelet therapy (aspirin + clopidogrel) β-blockers ACE inhibitors Statins Control risk factors ```

Management of STEMI - advice

No driving for 1 month after MI

Management of STEMI - CABG

Consider in patients w/ left main stem or three-vessel disease

Complications of ischaemic heart disease - general | 2

Increased risk of MI & other vascular disease (e.g. stroke, PVD) Cardiac injury from an MI can lead to heart failure & arrhythmias

Complications of ischaemic heart disease - early | 8

``` Death Cardiogenic shock Heart failure Ventricular arrhythmias Heart block Pericarditis Myocardial rupture Thromboembolism ```

Complications of ischaemic heart disease - late | 6

``` Ventricular wall rupture Valvular regurgitations Ventricular aneurysms Tamponade Dressler’s syndrome Thromboembolism ```

DARTH VADE pneumonic for...

Complications of ischaemic heart disease ``` Death Arrhythmias Rupture Tamponade Heart failure Valve disease Aneurysm Dressler’s syndrome Embolism ```

Prognosis of ischaemic heart disease | 2

``` TIMI score (0-7) can be used for risk stratification TIMI = thrombolysis in myocardial infarction High TIMI score associated w/ high risk of cardiac events within 30 days of MI ``` ``` Killip classification Class I: no evidence of heart failure Class II mild to moderate heart failure Class III: over pulmonary oedema Class IV: cardiogenic shock ```