STABLE ANGINA

✓ Medically ReviewedDISEASEID: MDBT0153🚨 TRIAGE: ROUTINEICD-10: I20.9

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Definition

CLINICAL DEFINITION

Stable angina is a clinical syndrome characterised by transient, predictable episodes of myocardial ischaemia, typically manifesting as chest discomfort or equivalent symptoms precipitated by exertion or emotional stress and relieved by rest or short-acting nitrates. It arises from a fixed atherosclerotic narrowing of one or more epicardial coronary arteries that limits blood flow during periods of increased myocardial oxygen demand.

IN PLAIN ENGLISH

Stable angina is a type of chest pain or discomfort that happens when your heart muscle does not get enough oxygen-rich blood, usually during physical activity or stress. It goes away with rest or specific medication, warning you that your heart arteries are narrowed.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

Stable angina is NOT a myocardial infarction, as it does not involve irreversible myocardial necrosis or elevated cardiac biomarkers. It is also NOT unstable angina, which occurs at rest, is new-onset and severe, or follows a crescendo pattern, indicating an acute coronary syndrome with plaque rupture.

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Word Breakdown

angina

=strangling, choking (from Greek 'agchone')

Literal Meaning: A strangling or choking sensation in the chest

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Abbreviations

CCS=Canadian Cardiovascular Society — grading system for angina severity

CAD=Coronary Artery Disease — underlying atherosclerotic pathology

IHD=Ischaemic Heart Disease — broader umbrella term for myocardial ischaemia

OMT=Optimal Medical Therapy — foundational pharmacological management

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Synonyms & Variants

Angina Pectoris›Chronic Coronary Syndrome›Stable Ischaemic Heart Disease›

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Category-Specific Context

As a chronic disease syndrome, stable angina represents the symptomatic manifestation of chronic coronary syndrome. It is classified by severity using systems like the Canadian Cardiovascular Society (CCS) grading scale, which stratifies risk and guides management based on the level of exertion required to provoke symptoms.

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Clinical Context & Usage

CLINICAL SETTINGS

Cardiology Outpatient ClinicGeneral PracticeEmergency DepartmentCardiac Rehabilitation Centre

USAGE & DOCUMENTATION NOTES

Clinicians typically document the precipitating factors, duration, and relieving factors of the pain. It is increasingly referred to as 'chronic coronary syndrome' in contemporary guidelines. Notes frequently include the CCS class (I-IV) to quantify functional limitation and guide therapeutic adjustments.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

Stable angina results from an imbalance between myocardial oxygen supply and demand. Atherosclerotic plaques cause fixed luminal narrowing of the epicardial coronary arteries, typically exceeding 70% stenosis. At rest, coronary blood flow is sufficient to meet basal metabolic needs. However, during physical exertion or emotional stress, increased heart rate, contractility, and wall tension elevate myocardial oxygen demand. The stenotic artery cannot adequately augment flow due to exhausted coronary vasodilatory reserve, leading to transient subendocardial ischaemia. This ischaemia triggers the release of metabolites such as adenosine and bradykinin that stimulate cardiac sympathetic afferent nerves, transmitting pain signals to the thalamus and cortex.

PRIMARY CAUSES

Coronary Atherosclerosis

Progressive accumulation of lipid-rich plaques in epicardial arteries causes fixed stenosis, limiting coronary flow reserve during exertion.

Coronary Microvascular Dysfunction

Impaired vasodilation and structural remodelling of the coronary microcirculation despite angiographically normal epicardial arteries, causing ischaemia (microvascular angina).

Myocardial Bridging

A band of heart muscle overlies a segment of a coronary artery, compressing it during systole and potentially causing exertional ischaemia due to delayed diastolic relaxation.

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Drug-Induced Causes

💊 Triptans (e.g., sumatriptan) ↗

Mechanism: Coronary vasospasm via 5-HT1B/1D receptor agonism, potentially precipitating angina in susceptible individuals.

→ Discontinue immediately; contraindicated in patients with known ischaemic heart disease.

💊 Ergot alkaloids (e.g., ergotamine) ↗

Mechanism: Potent coronary vasoconstriction reducing myocardial oxygen supply.

→ Stop offending agent; avoid use in patients with established coronary artery disease.

💊 Fluorouracil (5-FU) ↗

Mechanism: Coronary vasospasm or direct endothelial toxicity leading to acute ischaemia during infusion.

→ Stop infusion, administer nitrates or calcium channel blockers, and obtain urgent cardiology review.

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Epidemiology

Prevalence:Affects approximately 1-2% of the adult population in developed countries, with prevalence increasing significantly with age. It is estimated that over 100 million people worldwide suffer from chronic coronary syndromes.

Age Group:Primarily affects older adults, with incidence rising sharply after age 45 in men and age 55 in women.

Sex Predilection:Male

Geographic Distribution:Higher prevalence in high-income and middle-income countries associated with sedentary lifestyles and diets high in saturated fats, though the burden is rapidly increasing in low- and middle-income countries due to epidemiological transition.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 ROUTINE

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

New-onset severe angina or angina occurring at rest — Raises concern for Unstable Angina or Acute Coronary Syndrome; requires immediate ECG, troponin assessment, and urgent cardiology evaluation.
Angina equivalent (e.g., unexplained exertional dyspnoea, profound fatigue) in diabetic or elderly patients — May indicate severe multi-vessel or left main coronary disease without classic chest pain; requires prompt ischaemic evaluation.

URGENT EVALUATION TRIGGERS

Chest pain lasting >20 minutes at rest or unrelieved by sublingual nitrates.
Angina accompanied by haemodynamic instability (hypotension, syncope, new heart failure signs).
A sudden, marked increase in the frequency, severity, or duration of previously stable angina (crescendo pattern).

Contraindications & Precautions

CONTRAINDICATIONS

Phosphodiesterase-5 inhibitors (e.g.
sildenafil) — Absolute contraindication with concurrent nitrate therapy due to the risk of profound
refractory hypotension.
Non-dihydropyridine calcium channel blockers (verapamil
diltiazem) — Contraindicated in patients with severe heart failure with reduced ejection fraction or high-degree atrioventricular block.

SPECIAL PRECAUTIONS

Beta-blockers — Use with caution in patients with severe asthma or reactive airway disease (prefer cardioselective agents) and monitor for bradycardia.
Nitrates — Tolerance can develop with continuous exposure; ensure a daily nitrate-free interval of 10-12 hours to maintain efficacy.

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Myocardial Infarction — Plaque rupture and thrombosis can evolve stable angina into an acute coronary syndrome.
Heart Failure — Chronic ischaemia or subsequent infarctions can lead to left ventricular systolic or diastolic dysfunction (ischaemic cardiomyopathy).
Arrhythmias — Ischaemic scar tissue or acute ischaemic episodes can precipitate ventricular tachycardia or fibrillation.

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

Unstable Angina

Sounds similar and represents the same disease spectrum, but unstable angina occurs at rest or with a crescendo pattern and constitutes an acute coronary syndrome requiring urgent intervention.

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Gastro-oesophageal Reflux Disease (GORD)

Key Distinguishing Feature: Burning retrosternal pain, often postprandial or when supine, relieved by antacids; lacks exertional trigger.

Musculoskeletal Pain (Costochondritis)

Key Distinguishing Feature: Pain is reproducible with palpation or specific torso movements; sharp rather than pressure-like.

Pericarditis

Key Distinguishing Feature: Pleuritic chest pain that improves when leaning forward; ECG shows diffuse PR depression and ST elevation.

Aortic Stenosis

Key Distinguishing Feature: Exertional angina accompanied by syncope or heart failure, harsh ejection systolic murmur radiating to carotids.

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Clinical Pearls

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Angina is a clinical diagnosis based on the history of exertional chest discomfort relieved by rest; a normal resting ECG does not exclude stable angina, as the ECG is frequently normal when the patient is pain-free.

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Not all patients experience classic 'chest pain'; women, the elderly, and patients with diabetes frequently present with 'angina equivalents' such as exertional dyspnoea, jaw pain, or profound fatigue.

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The Canadian Cardiovascular Society (CCS) classification is highly useful for tracking disease progression: Class I (only strenuous exertion), Class II (slight limitation), Class III (marked limitation), Class IV (inability to carry on any physical activity without discomfort).

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Optimal medical therapy (OMT) including high-intensity statins, antiplatelet agents, and anti-anginals is the foundation of management; revascularisation in stable disease is primarily indicated for symptom relief refractory to OMT, or to improve survival in specific high-risk anatomies.

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Example Usage & SOAP

CLINICAL SENTENCE

"The patient is a 65-year-old male with a six-month history of CCS Class II stable angina, reporting substernal pressure radiating to the left arm after walking two blocks, which consistently resolves within five minutes of rest."

IN A SOAP NOTE

S: 62 y/o M with known CAD presents for routine follow-up. Reports predictable substernal chest heaviness when walking uphill, lasting ~5 mins, relieved by rest or sublingual GTN. Denies rest pain or syncope. O: BP 128/78 mmHg, HR 64 bpm regular. Cardiovascular exam: normal S1/S2, no murmurs. Resting ECG: normal sinus rhythm, no ST-T wave changes. A: Stable angina pectoris, currently well-controlled on medical therapy (CCS Class II). P: Continue bisoprolol 5mg OD, atorvastatin 40mg OD, aspirin 75mg OD, and PRN GTN spray. Encourage regular moderate aerobic exercise. Review in 6 months or sooner if symptoms worsen.

DIFFERENTIAL DIAGNOSIS CONTEXT

Differential for exertional chest pain: (1) Stable Angina — predictable, exertional, relieved by rest/nitrates, fixed stenosis; (2) Aortic Stenosis — exertional angina with syncope or heart failure, harsh ejection systolic murmur; (3) Hypertrophic Cardiomyopathy — exertional pain in young patient, family history of sudden cardiac death, jerky pulse; (4) GORD — burning pain, postprandial, no exertional correlation.

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Classifications & Scoring

GRADING SYSTEM

Canadian Cardiovascular Society (CCS) Angina Classification

Grades the severity of angina pectoris based on physical activity limitations. Class I: ordinary physical activity does not cause angina. Class II: slight limitation of ordinary activity. Class III: marked limitation of ordinary physical activity. Class IV: inability to carry on any physical activity without discomfort.

SCORING TOOL

Diamond-Forrester Classification

Estimates the pre-test probability of obstructive coronary artery disease based on the nature of chest pain (typical, atypical, non-anginal), age, and sex, guiding the need for further diagnostic testing.

SCORING TOOL

Duke Treadmill Score

Prognostic scoring system calculated from exercise treadmill test results (exercise time, max ST deviation, and angina index) to stratify mortality risk in patients with suspected or known stable angina.

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Prognosis

SHORT-TERM OUTCOME

Generally favourable with optimal medical therapy and lifestyle modification; annual mortality rate is typically 1-2% in stable patients without high-risk anatomical features.

LONG-TERM PROGNOSIS

Dependent on the extent of coronary disease, left ventricular function, and comorbidities. Patients with multi-vessel or left main disease have a higher long-term risk of cardiovascular death, which may be improved with revascularisation in specific high-risk cohorts.

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References & Coding

ICD-10 DIAGNOSTIC CODE

I20.9

LITERATURE CITATIONS & GUIDELINES

[1]Knuuti J, Wijns W, Saraste A, et al. 2019 ESC Guidelines for the diagnosis and management of chronic coronary syndromes. Eur Heart J. 2020;41(3):407-477.

[2]Fihn SD, Gardin JM, Abrams J, et al. 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the diagnosis and management of patients with stable ischemic heart disease. J Am Coll Cardiol. 2012;60(24):e44-e164.

[3]Campeau L. Letter: Grading of angina pectoris. Circulation. 1976;54(3):522-523.

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.