Angina Pectoris

Following on from my last post on Acute Coronary Syndrome, this should have probably come first, but heart attacks tend to get more press than angina anyway so….


Angina Pectoris

Definition:

Stable angina: forms part of ischaemic heart disease, along with ACS. Chest pain induced by effort, relieved by rest.

Unstable angina: angina of increasing frequency or severity, occurs on minimal exertion or at rest, associated with increased risk of MI. (Part of ACS)

Decubitus angina: precipitated by lying flat.

Variant (Prinzmetal’s) angina: caused by coronary artery spasm (rare, may coexist with fixed stenosis)

Aetiology/ risk factors:

-due to myocardial ischaemia, as increased myocardial oxygen demands are not met during exertion

-mostly caused by atheroma

-rarely: anaemia, aortic stenosis, tachyarrhythmias, hypertrophic cardiomyopathy, arteritis/ small vessel disease (microvascular angina/ cardiac syndrome X), coronary artery spasm (e.g. cocaine)

Risk factors: male, diabetes, family history, hypertension, hyperlipidaemia, smoking

Epidemiology: common, more so in males

Symptoms:

-central chest tightness or heaviness, brought on by exertion and relieved by rest (distinguishes from ACS)

-may radiate to one or both arms, the neck, jaw, or teeth

-may be precipitated by emotion, cold weather, and heavy meals

-associated symptoms: dyspnoea, nausea, sweatiness, faintness

Prinzmetal angina: pain usually occurs during rest, rather than during activity

Signs:

Signs of risk factors e.g. corneal arcus and xanthelasma in hyperlipidaemia Image result for corneal arcus and xanthelasma

Image result for xanthelasma

Xanthelasma (lipid deposits around eye)

 

 

 

 

Investigations:

ECG: usually normal

             may show ST depression, flat or inverted T waves, signs of past MI (e.g. Q waves)

Prinzmetal angina- ECG during pain shows ST segment elevation, which resolves as the pain subsides

Exclude precipitating factors: anaemia (FBC), diabetes (blood glucose), hyperlipidaemia (lipids), thyrotoxicosis (TFTs), temporal arteritis (biopsy).

-Some units routinely do exercise tolerance tests on those < 70 years old but NICE suggests that they should only be done where there is diagnostic uncertainty in people with known CAD (e.g. previous MI or angioplasty)

Known Coronary Artery Disease (CAD):

-Typical pain = no further investigation

-Atypical pain = exercise testing or

functional imaging– myocardial perfusion scintigraphy, stress echo/ MRI

Unknown CAD: stratify likelihood of CAD

> 90%  treat as known CAD

61-90% angiography, or functional imaging if inappropriate

30-60% functional imaging (myocardial perfusion scintigraphy, stress echo/ MRI)

10-29% coronary artery calcification score with CT

< 10% reconsider diagnosis

Angiography: insert catheter into heart coronary vessels via the femoral or radial artery, inject radiopaque contrast medium to image coronary arteries.

Exercise ECG testing: treadmill test using a protocol, most commonly Bruce protocol. Test is positive if ≥ 1 mm horizontal or downsloping ST segment depression measured.

Radionuclide myocardial perfusion imaging (scintigraphy): give radionuclide and perform scan under stress (exercise or pharmacological- dobutamine, adenosine, dipyridamole). Would show low uptake in ischaemic myocardium.

Stress echo: exercise or dobutamine/ dipyramidole stress, echo may detect inducible wall motion abnormalities

Coronary calcium scoring: uses specialised CT

Management:

Modify risk factors: stop smoking, exercise, weight loss. Control hypertension, diabetes. Statin if total cholesterol > 4 mmol/L.

Aspirin (75-150mg/24h)

Beta blockers- e.g. atenolol (50-100mg/24h), reduces symptoms- CI in coronary artery spasm

Nitratesfor symptoms, GTN (spray or sublingual tablets) up to every 30 mins

              – prophylaxis, regular oral nitrate e.g. isosorbide mononitrate (20-40 mg PO bd)

Long acting calcium antagonist- amlodipine (10mg/24h), diltiazem (90-180 mg/12h). Useful if contraindication to beta blocker.

K+ channel activator- e.g. nicorandil (10-30 mg/12h), if still not controlled.

Others: ivabridine, trimetazidine, ranolazine

Referral indications: diagnostic uncertainty, new angina of sudden onset, recurrent angina if past MI or CABG, angina uncontrolled by drugs, unstable angina

Percutaneous transluminal coronary angioplasty (PTCA): involves balloon dilation of the stenotic vessel(s).

Indications: poor response to medical therapy, refractory angina in patients not suitable for CABG, previous CABG.

+/- coronary stenting.

               + antiplatelets to reduce risk of stent thrombosis e.g. clopidogrel + aspirin

 + IV glycoprotein IIb/IIIa inhibitors (eptifibatide) to reduce procedure related ischaemic events

Coronary Bypass Graft (CABG)- for more severe cases (three-vessel disease)

Prinzmetal angina: calcium channel blockers +/- long acting nitrates

                                  Aspirin can aggravate the ischaemic attacks

                                 Beta blockers can increase vasospasm- avoid

Complications:

-progression to acute coronary syndrome

Prognosis:

-properly managed, 58% of patients free of angina within 1 year

-some patients may experience recurrence or worsening of angina symptoms due to progression of atherosclerotic disease

References: Cheese & Onion, Rapid Medicine, BMJ best practice
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