Lucan · Conditions

Stable angina pectoris

Australian guidance: Heart Foundation Stable CHD Guidelines

1. Definition and epidemiology

Stable angina is a clinical syndrome characterised by retrosternal chest discomfort provoked by physical exertion or emotional stress, lasting 10 minutes or less, and resolving promptly with rest or sublingual glyceryl trinitrate. It is considered stable when the symptom pattern has not changed over the preceding month. Ischaemic heart disease affects an estimated 1.4 million Australians; stable angina is the most common chronic manifestation and places these patients in the high cardiovascular risk category.

2. Pathophysiology

Stable angina arises from a fixed reduction in coronary artery lumen diameter due to atherosclerotic plaque. As detailed in Robbins Ch 11, atherosclerosis involves endothelial injury, subintimal lipoprotein deposition, macrophage foam cell accumulation, smooth muscle migration, and fibrous cap formation over a lipid-rich core. The result is a stable plaque that narrows the vessel lumen by 70% or more before causing ischaemia at rest; lesser degrees of stenosis cause ischaemia only when myocardial oxygen demand rises with exertion. When demand exceeds the fixed supply capacity, myocytes shift to anaerobic metabolism, accumulate lactate and adenosine, and activate afferent pain fibres via the cardiac sympathetic plexus, producing the characteristic retrosternal pressure or tightness that radiates to the left arm, jaw, or back. Conditions that independently raise demand or reduce supply, including anaemia, aortic stenosis, thyrotoxicosis, and hypertrophic cardiomyopathy, can unmask or worsen angina in the setting of only moderate coronary stenosis and must be considered before a diagnosis of stable angina is finalised.

3. Clinical presentation and diagnostic criteria

The typical history is of retrosternal tightness or pressure lasting 2 to 10 minutes, brought on by a predictable level of exertion (walking uphill, cold weather, emotional arousal) and relieved by rest or sublingual glyceryl trinitrate. Radiation to the left arm, neck, or jaw is common; dyspnoea may be an anginal equivalent in older adults and people with diabetes. The symptom pattern must have been unchanged for at least one month. On examination, findings between episodes are often normal; signs of precipitating conditions such as anaemia or aortic stenosis should be sought. Atypical presentations are more common in women, older adults, and First Nations Australians.

4. Investigations and AU-specific cutoffs

The initial evaluation proceeds in a structured order.

Baseline bloods: Full blood count to exclude anaemia; fasting lipids and glucose to characterise cardiovascular risk; thyroid function tests if thyrotoxicosis is possible; HbA1c if diabetes is suspected or known.

Resting 12-lead ECG: Performed in all patients. May show prior Q waves, ST changes, left ventricular hypertrophy, or bundle branch block; a normal resting ECG does not exclude significant coronary artery disease.

CVD risk quantification: The Aus CVD Risk Calculator (based on the PREDICT-1 equation, recalibrated for the Australian population) is used to estimate 5-year cardiovascular event probability in adults aged 45 to 79 years without known CVD. Risk categories are high (5-year risk 10% or more), intermediate (5 to less than 10%), and low (less than 5%). Patients with stable angina already have known atherosclerotic cardiovascular disease and are therefore managed as high risk without requiring the calculator.

Functional or anatomical imaging: Exercise stress ECG remains commonly used for functional assessment; however, CT coronary angiography is increasingly preferred as the initial imaging modality because of its high negative predictive value. Nuclear myocardial perfusion imaging, stress echocardiography, or invasive coronary angiography are used when CT coronary angiography is inconclusive or when revascularisation is being considered.

Echocardiogram: Obtained if there is suspicion of valvular heart disease or left ventricular dysfunction, or to assess ejection fraction before initiating beta blockers.

5. Management

Management has two parallel goals: relieving symptoms and preventing cardiovascular events.

Lifestyle and risk factor modification: All patients should be supported to achieve smoking cessation, healthy dietary patterns, regular moderate physical activity, and optimal body weight. Blood pressure should be treated to target, dyslipidaemia managed per lipid guidelines, and diabetes optimised. Patients should also be screened for depression, which is independently associated with worse cardiovascular outcomes, and referred to cardiac rehabilitation where appropriate. Annual influenza vaccination is recommended for all patients with atherosclerotic cardiovascular disease.

Antiplatelet and statin therapy (secondary prevention core): Aspirin 100 to 150 mg orally daily is the standard antiplatelet agent for all patients with established coronary artery disease. Clopidogrel 75 mg daily is an alternative in patients intolerant of aspirin. Low-intensity rivaroxaban 2.5 mg twice daily added to aspirin can be considered in selected high-risk patients with stable coronary artery disease, particularly those with polyvascular disease or chronic kidney disease, after specialist review of bleeding risk. High-intensity statin therapy is recommended regardless of baseline lipid levels.

Antianginal therapy: A stepwise approach is used. Beta blockers are first-line for prevention of anginal episodes by reducing myocardial oxygen demand; atenolol 25 to 100 mg daily or metoprolol tartrate 25 to 100 mg two to three times daily are the standard agents. If beta blockers are contraindicated or not tolerated, a nondihydropyridine calcium channel blocker (diltiazem modified-release or verapamil modified-release) can be substituted; diltiazem and verapamil must not be combined with a beta blocker due to the risk of severe bradycardia and heart failure. If single-agent therapy is insufficient, a dihydropyridine calcium channel blocker (amlodipine 2.5 to 10 mg daily or nifedipine modified-release 30 to 90 mg daily) can be added to a beta blocker. Long-acting nitrates can be added as a third agent but do not improve survival and require a daily nitrate-free interval to avoid tolerance.

Revascularisation: Percutaneous coronary intervention or coronary artery bypass grafting is considered when symptoms persist despite optimal medical therapy, or when anatomy indicates a survival benefit (left main disease, three-vessel disease with reduced ejection fraction).

Acute episode management: Patients should be prescribed sublingual glyceryl trinitrate and given a written chest pain action plan. If pain persists beyond 10 minutes despite two doses, a third dose should be taken and an ambulance called immediately.

6. Pharmacology and AU PBS notes

Beta blockers (first-line antianginal): Atenolol (Tenormin, generics) 25 to 100 mg orally daily; metoprolol tartrate (Lopressor, generics) 25 to 100 mg two to three times daily. In patients with left ventricular ejection fraction of 40% or less, substitute a heart-failure beta blocker: bisoprolol, carvedilol, nebivolol, or metoprolol succinate.

Calcium channel blockers: Diltiazem modified-release (Cardizem CD, generics) 180 to 360 mg daily; verapamil modified-release (Isoptin SR, generics) 120 to 480 mg daily; amlodipine (Norvasc, generics) 2.5 to 10 mg daily; nifedipine modified-release (Adalat Oros, generics) 30 to 90 mg daily.

Nitrates: Glyceryl trinitrate spray 400 micrograms sublingually for acute episodes (up to 3 doses, 5 minutes apart); glyceryl trinitrate patch 5 to 20 mg transdermally, worn for a maximum of 14 hours per 24-hour period to maintain a nitrate-free interval; isosorbide mononitrate modified-release 30 to 120 mg orally daily.

Antiplatelet: Aspirin 100 mg is listed on the PBS as a general benefit item; clopidogrel 75 mg is PBS listed (Authority Required, streamlined) for patients with established coronary artery disease intolerant of aspirin.

Statins (secondary prevention): High-intensity statins (rosuvastatin 20 to 40 mg or atorvastatin 40 to 80 mg) are PBS listed (Authority Required, streamlined) for patients with established coronary artery disease.

Third-line agents: Nicorandil 5 to 20 mg twice daily and perhexiline (specialist supervised) are available on the PBS for refractory angina.

7. Complications and monitoring

Acute coronary syndrome: The principal risk is plaque rupture converting stable angina to an acute coronary syndrome. Any change in the pattern of symptoms (increased frequency, lower exertion threshold, rest pain, nocturnal pain) must trigger urgent reassessment.

Left ventricular dysfunction: Repeated ischaemic episodes can produce hibernating myocardium and progressive systolic dysfunction. Echocardiography should be repeated if new symptoms of heart failure develop.

Arrhythmia: Ischaemia is a substrate for ventricular arrhythmia; surveillance with a resting ECG at each review appointment is appropriate.

Monitoring schedule: At each review, assess symptom stability, medication tolerability, blood pressure, heart rate, and lipid targets. Repeat fasting lipids 4 to 6 weeks after initiating or intensifying statin therapy, then annually. All patients with established stable angina are classified as high CVD risk; formal recalculation using the Aus CVD Risk Calculator is not generally required.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.