Chronic Coronary Syndrome

Stable phase of coronary artery disease: exertional angina from fixed obstruction, vasospastic or microvascular angina, ischaemic cardiomyopathy, or asymptomatic disease after revascularisation.

• Mechanism: flow limiting atherosclerotic stenosis (usually greater than 70%, or left main greater than 50%), endothelial dysfunction, or microvascular disease.
• Angina affects a few percent of middle aged adults. Annual cardiac death or infarction is about 1 to 3%.

• Central chest tightness on exertion or emotion, relieved by rest or glyceryl trinitrate within minutes. Radiation to arm, jaw or neck.
• Dyspnoea, fatigue, or reduced exercise tolerance may be the only symptom.
• Examination: often normal. Look for xanthelasma, carotid bruits, signs of heart failure, anaemia, and aortic stenosis.
• Differential diagnosis: oesophageal reflux, musculoskeletal pain, anxiety, anaemia, aortic stenosis, hypertrophic cardiomyopathy, pulmonary disease.
• Complications: acute coronary syndrome, heart failure, arrhythmia, sudden death.

• Assess pre-test probability from age, sex and symptom type.
• Resting ECG (Q waves, ST-T changes), echocardiography, fasting lipids, HbA1c, full blood count, renal and thyroid function.
• Intermediate probability: coronary CT angiography (calcium score and stenosis grading), or functional testing (stress echocardiography, perfusion imaging, magnetic resonance perfusion).
• High probability or severe symptoms: invasive angiography with fractional flow reserve (abnormal at 0.80 or less) or instantaneous wave free ratio (abnormal at 0.89 or less).
• Suspected vasospasm or microvascular disease with non-obstructed arteries: acetylcholine provocation and coronary flow reserve testing.

• Lifestyle: smoking cessation, 150 minutes of moderate exercise weekly, weight control, Mediterranean type diet.
• Sublingual glyceryl trinitrate 0.4 mg for attacks: sit down, repeat after 5 minutes, call for help if pain continues 5 minutes after the second dose. Never combine with phosphodiesterase-5 inhibitors (avoid for 24 to 48 hours).
• Symptom control (start one or two agents):
  • Bisoprolol 2.5 to 10 mg daily or metoprolol succinate 50 to 200 mg daily, aiming for resting heart rate 55 to 60 beats/min.
  • Amlodipine 5 to 10 mg daily, or diltiazem modified release 90 to 360 mg daily (avoid with heart failure with reduced ejection fraction, and with a beta blocker in conduction disease).
  • Isosorbide mononitrate modified release 30 to 120 mg each morning with a nitrate free interval of 10 to 14 hours.
  • Ivabradine 5 mg twice daily, increased to 7.5 mg twice daily (sinus rhythm, resting heart rate greater than 70).
  • Ranolazine 375 mg twice daily increased to 500 then 750 mg twice daily (avoid with severe renal or hepatic impairment and with QT-prolonging drugs).
  • Nicorandil 10 to 20 mg twice daily (avoid with phosphodiesterase-5 inhibitors; risk of oral and gastrointestinal ulceration).
  • Trimetazidine 35 mg modified release twice daily (contraindicated with Parkinson disease, tremor and severe renal impairment).
• Event prevention:
  • Aspirin 75 to 100 mg daily; clopidogrel 75 mg daily if aspirin is not tolerated.
  • Atorvastatin 40 to 80 mg daily with target LDL cholesterol less than 1.4 mmol/L; add ezetimibe 10 mg then a PCSK9 inhibitor if not reached.
  • Ramipril 2.5 to 10 mg daily with diabetes, hypertension, chronic kidney disease or reduced ejection fraction.
  • Blood pressure target less than 130/80 mmHg; HbA1c individualised, usually 48 to 58 mmol/mol (6.5 to 7.5%).
  • High ischaemic risk and low bleeding risk: add rivaroxaban 2.5 mg twice daily to aspirin.
  • Low dose colchicine 0.5 mg daily may reduce events; avoid in severe renal or hepatic impairment and with strong CYP3A4 or P-glycoprotein inhibitors. Evidence is still developing.
• Revascularisation indications: left main stenosis greater than 50%, proximal left anterior descending disease, three vessel disease with diabetes or reduced ejection fraction, ischaemia over more than 10% of myocardium, or symptoms refractory to maximal medical therapy. Choose PCI or bypass surgery by anatomy, diabetes, and surgical risk.
• After elective PCI: aspirin plus clopidogrel 75 mg daily for 6 months (1 to 3 months if bleeding risk is high), then a single antiplatelet.
• Special groups: elderly (low dose start, check postural BP); renal impairment (adjust ranolazine and enoxaparin, protect against contrast injury); women with microvascular disease (beta blocker, calcium channel blocker, statin, ACE inhibitor).
• Red flags: change to a rest or crescendo pattern, pain lasting more than 20 minutes, syncope, new heart failure. These need same day assessment for acute coronary syndrome.
• Follow up every 6 to 12 months: symptoms, blood pressure, lipids, renal function, adherence. Repeat imaging only for a change in symptoms.