💡 In people with angina-like symptoms but no flow-limiting epicardial coronary disease, consider microvascular angina, historically called Cardiac Syndrome X. Not all angina is caused by large-vessel coronary stenosis; ischaemia can also arise from microvascular dysfunction, vasospasm, or supply-demand mismatch.

📖 About

Stable angina is chest discomfort caused by transient myocardial ischaemia, usually due to atherosclerotic coronary artery disease.
Symptoms are classically predictable, brought on by exertion or emotional stress, and relieved by rest or glyceryl trinitrate (GTN) within minutes.
Angina may also occur because of microvascular dysfunction, coronary vasomotor disorders, or conditions that increase myocardial oxygen demand or reduce oxygen supply.
Do not use response to GTN alone to diagnose angina; it supports the story but is not diagnostic by itself.

🧬 Causes

Obstructive coronary artery disease due to atherosclerotic plaque.
Microvascular angina with no obstructive epicardial coronary stenosis.
Coronary vasospasm, including vasospastic / Prinzmetal angina.
Supply-demand mismatch: aortic stenosis, hypertrophic cardiomyopathy, anaemia, tachyarrhythmia, fever, thyrotoxicosis, or severe hypertension.

🩺 NICE Clinical Classification of Chest Pain

Type	Features
Typical angina	All 3 features: Constricting discomfort in the front of the chest, neck, shoulders, jaw, or arms Precipitated by physical exertion Relieved by rest or GTN within about 5 minutes
Atypical angina	Only 2 of the 3 anginal features are present.
Non-anginal chest pain	Only 1 or none of the 3 anginal features are present.

📊 Canadian Cardiovascular Society (CCS) Angina Class

Class I: Angina only with strenuous, rapid, or prolonged exertion.
Class II: Slight limitation of ordinary activity.
Class III: Marked limitation of ordinary physical activity.
Class IV: Symptoms at rest or with minimal activity.

⚠️ Cardiovascular Risk Factors

Smoking
Hypertension
Dyslipidaemia
Diabetes mellitus
Obesity and physical inactivity
Increasing age
Male sex
Family history of premature coronary disease
Previous myocardial infarction, coronary revascularisation, or established cardiovascular disease

🔑 Risk-factor modification is central: smoking cessation, blood pressure control, lipid lowering, diabetes management, exercise, and weight optimisation reduce future cardiovascular events.

🩺 Clinical Features

Central chest tightness, pressure, heaviness, or constriction.
Triggered by exertion, cold weather, emotional stress, or heavy meals.
Relieved by rest or GTN within about 5 minutes.
May radiate to the left arm, both arms, jaw, neck, back, or epigastrium.
Associated breathlessness, nausea, sweating, or collapse should raise concern for acute coronary syndrome, especially if symptoms are prolonged, new, worsening, or occurring at rest.

🖥️ CT coronary angiography (CTCA) is the recommended first-line anatomical test in NICE guidance when stable angina cannot be excluded clinically. It should be offered when the history suggests typical or atypical angina, or when symptoms are non-anginal but the resting ECG shows ST-T changes or Q waves. CTCA is particularly useful because it can identify coronary atheroma, estimate stenosis severity, and has a high negative predictive value for obstructive epicardial coronary disease. It does not directly measure ischaemia, so functional imaging may be needed if CTCA shows disease of uncertain functional significance or is non-diagnostic.

🔥 Precipitants / Aggravating Factors

Physical exertion
Emotional stress
Cold exposure
Heavy meals or post-prandial exertion
Anaemia, tachyarrhythmia, fever, thyrotoxicosis

🔍 Differentials

Acute coronary syndrome
Aortic stenosis
Hypertrophic cardiomyopathy
Coronary vasospasm
Microvascular angina / Cardiac Syndrome X
Gastro-oesophageal reflux disease or oesophageal spasm
Musculoskeletal chest pain
Pulmonary embolism
Aortic dissection
Pneumonia or pneumothorax

🧪 Investigations

Assess first for ACS if symptoms are new, prolonged, severe, worsening, occurring at rest, or associated with autonomic symptoms, breathlessness, haemodynamic instability, or ECG changes.
12-lead ECG as part of initial assessment; do not rule out stable angina or ACS on the basis of a normal ECG alone.
Blood tests to identify contributors such as anaemia and to assess cardiovascular risk.
CT coronary angiography (CTCA) is the recommended first-line anatomical test when recent-onset stable angina cannot be excluded clinically.
Functional imaging may be needed if CTCA shows coronary disease of uncertain functional significance or is non-diagnostic.
Invasive coronary angiography may be needed if functional imaging is inconclusive or when revascularisation is being considered.
Do not use exercise ECG to diagnose or exclude stable angina in people without known coronary artery disease.
Echocardiography is useful if valve disease, cardiomyopathy, heart failure, or LV dysfunction is suspected.
Chest X-ray is not routine for stable angina, but consider it if another diagnosis such as lung tumour, pneumonia, pneumothorax, or heart failure is suspected.

📈 Risk / Severity Clues

New, worsening, prolonged, or rest pain suggests unstable angina / ACS rather than stable angina.
Poor LV function, extensive ischaemia, left main stem disease, proximal three-vessel disease, or anatomically complex coronary disease increases risk.
Always decide first whether the presentation could represent ACS; stable angina is a diagnosis for intermittent, predictable symptoms once ACS is not suspected.

💊 Management

Lifestyle and prevention: smoking cessation, exercise, weight reduction, healthy diet, and treatment of hypertension, lipids, and diabetes.
Short-acting nitrate: offer GTN for preventing and treating episodes of angina. Advise the patient to use it before predictable exertion and to repeat after 5 minutes if pain persists.
Emergency advice: if pain has not gone 5 minutes after a second GTN dose, call an emergency ambulance.
First-line anti-anginal therapy: offer either a beta-blocker or a calcium-channel blocker, chosen according to comorbidities, contraindications, and patient preference.
If symptoms are not controlled, consider switching to the other class or combining a beta-blocker with a dihydropyridine calcium-channel blocker such as amlodipine, felodipine, or modified-release nifedipine.
If beta-blockers and calcium-channel blockers are contraindicated or not tolerated, consider long-acting nitrate, ivabradine, nicorandil, or ranolazine.
Aspirin 75 mg daily may be considered after weighing bleeding risk and comorbidities.
Statin therapy should be offered in line with lipid-modification guidance.
ACE inhibitor should be considered in people with stable angina and diabetes, and continued if indicated for other conditions such as hypertension, CKD, or heart failure.

💊 Stable Angina — Common Medications and Adult Doses

⚠️ Prescribing caution: doses below are typical adult starting / titration doses for stable angina. Always check the current BNF, renal and hepatic function, heart rate, blood pressure, frailty, drug interactions, contraindications and local formulary before prescribing.

Drug class	Medication	Usual adult dose	Key cautions / notes
Rapid symptom relief	Glyceryl trinitrate (GTN) sublingual spray	1–2 sprays under the tongue for angina. Repeat after 5 minutes if pain persists. Use before predictable exertion.	Advise patient to sit down before use. Can cause headache, flushing, dizziness and hypotension. Avoid with PDE-5 inhibitors such as sildenafil/tadalafil because of severe hypotension risk. If pain persists despite repeat GTN, treat as possible ACS.
Rapid symptom relief	GTN sublingual tablet	Usually 300–600 micrograms sublingually when required.	Tablets have a short expiry once opened. Spray is often more practical for patients.
First-line anti-anginal	Bisoprolol	Start 5 mg once daily. Usual maintenance 10 mg once daily. Maximum often 20 mg once daily.	Avoid or use caution in bradycardia, heart block, decompensated heart failure, severe asthma/COPD with bronchospasm. Useful if tachycardic or previous MI.
First-line anti-anginal	Atenolol	Usually 50–100 mg daily, either once daily or divided.	Renally cleared, so dose caution in renal impairment. Less commonly preferred than bisoprolol in many UK formularies.
First-line anti-anginal	Amlodipine	Start 5 mg once daily. Increase to 10 mg once daily if needed.	Dihydropyridine calcium-channel blocker. Useful with beta-blocker if additional control needed. Can cause ankle oedema, flushing and headache.
First-line anti-anginal	Diltiazem modified-release	Commonly 90–120 mg twice daily, titrated according to preparation and response.	Rate-limiting calcium-channel blocker. Avoid combining with beta-blockers unless specialist advice because of bradycardia/heart block risk. Prescribe MR preparations by brand where required.
First-line anti-anginal	Verapamil	Immediate-release: 80–120 mg three times daily. Modified-release doses vary by preparation.	Avoid with beta-blockers. Can cause constipation, bradycardia and heart block. Avoid in significant LV systolic dysfunction.
Add-on / alternative anti-anginal	Isosorbide mononitrate immediate-release	Start 10 mg twice daily. Increase if needed up to around 120 mg daily in divided doses.	Use asymmetric dosing to allow a nitrate-free interval and reduce tolerance. Headache and hypotension are common.
Add-on / alternative anti-anginal	Isosorbide mononitrate modified-release	Commonly 30–60 mg once daily in the morning. May increase according to response and preparation.	Useful for prophylaxis rather than acute relief. Ensure nitrate-free interval to reduce tolerance.
Add-on / alternative anti-anginal	Nicorandil	Start 5–10 mg twice daily. Increase if tolerated, commonly to 20 mg twice daily; higher doses may be used specialist-led.	Second-line option. Can cause headache, flushing and hypotension. Important adverse effect: painful mucosal, skin, gastrointestinal or perianal ulceration.
Add-on / alternative anti-anginal	Ranolazine	Start 375 mg twice daily for 2–4 weeks. Increase to 500 mg twice daily. Maximum 750 mg twice daily.	Useful if heart rate or BP limits other drugs. Check interactions and QT risk. Avoid or reduce dose in significant renal/hepatic impairment depending on severity.
Add-on / alternative anti-anginal	Ivabradine	Usually 2.5–5 mg twice daily initially. Increase if needed up to 7.5 mg twice daily.	Only works in sinus rhythm. Avoid in bradycardia and monitor for AF, visual symptoms and excessive HR reduction. Usually specialist/formulary restricted.
Secondary prevention	Aspirin	Usually 75 mg once daily.	Consider bleeding risk, dyspepsia, anticoagulation, allergy and need for gastroprotection. Use if CAD/atheroma risk justifies it.
Secondary prevention	Atorvastatin	Often 80 mg once daily for established cardiovascular disease, unless contraindicated or not tolerated.	Dose may need adjustment for frailty, interactions, liver disease or intolerance. Follow lipid-modification guidance.
Secondary prevention / comorbidity	ACE inhibitor e.g. ramipril	Start low, for example 1.25–2.5 mg once daily. Titrate gradually, often toward 10 mg daily if tolerated and indicated.	Particularly consider in diabetes, hypertension, CKD, LV dysfunction or heart failure. Monitor U&Es, creatinine and potassium after initiation and dose changes.

🧠 Practical Prescribing Pearls

🫀 First-line symptom prevention: beta-blocker or calcium-channel blocker.
➕ If control is poor, combine a beta-blocker with a dihydropyridine CCB such as amlodipine; avoid beta-blocker + verapamil/diltiazem unless specialist-directed.
💥 GTN is for attacks; long-acting nitrates are for prevention.
⏱️ Long-acting nitrates need a nitrate-free interval to prevent tolerance.
🚨 New, worsening, prolonged, or rest pain should be treated as possible acute coronary syndrome, not simple stable angina.

🔧 Revascularisation

Consider PCI or CABG if symptoms are not satisfactorily controlled with optimal medical treatment.
Offer coronary angiography to guide treatment strategy when symptoms remain uncontrolled despite optimal medical therapy.
The choice between PCI and CABG depends on coronary anatomy, comorbidity, diabetes, age, symptom burden, left main stem or multivessel disease, and cardiology / MDT assessment.
In some patients with left main stem disease or proximal three-vessel disease, CABG may provide a prognostic advantage as well as symptom relief.

🫀 Microvascular Angina / Cardiac Syndrome X

Consider when anginal symptoms persist but angiography or CTCA does not show flow-limiting epicardial coronary disease.
Symptoms may be exertional and typical, despite apparently normal large coronary arteries.
Continue anti-anginal drug treatment only if it improves symptoms.
Do not routinely offer secondary-prevention drugs solely for suspected Cardiac Syndrome X unless there is another indication, such as atherosclerotic disease, diabetes, hypertension, or raised cardiovascular risk.

💡 Clinical Pearls

Stable angina is predictable and exertional; unstable angina is new, worsening, prolonged, or occurs at rest and should be treated as ACS until proven otherwise.
Exercise treadmill testing is no longer the routine diagnostic test for suspected stable angina in NICE guidance.
CTCA is anatomical; functional imaging assesses inducible ischaemia.
Microvascular angina is a real ischaemic syndrome even when the major coronary arteries look normal.

📚 References

NICE CG95: Recent-onset chest pain of suspected cardiac origin: assessment and diagnosis.
NICE CG126: Stable angina: management.
British Heart Foundation: Microvascular angina.

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IHD: Chronic stable angina ✅