stable angina & chronic coronary syndromes

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ischaemic cascade

With increasing ischaemic duration, abnormalities appear in a predictable sequence:

1. perfusion abnormality (seen on myocardial perfusion imaging)
2. diastolic dysfunction → systolic dysfunction (wall motion abnormalities)
3. ECG changes (ST depression/elevation)
4. symptoms (angina)
5. myocardial necrosis (troponin release)

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diagnosis — choosing the right test

All stable CAD patients require resting LVEF imaging (e.g. TTE) — CCS 2014.

functional testing (non-invasive stress tests)

Two components to every stress test:

Component	Options
Stress	exercise (preferred) or pharmacologic (dobutamine, vasodilators)
Test	ECG alone, ECG + echo, ECG + nuclear (SPECT)

Choosing the stress modality:

• exercise whenever possible — provides prognostic data (METs achieved, duration, haemodynamic response)
• pharmacologic if unable to exercise adequately

Choosing the imaging modality:

• ECG alone if baseline ECG is interpretable
• add imaging (echo or nuclear) if ECG uninterpretable: LBBB, paced rhythm, pre-excitation, significant baseline ST changes
• RBBB is generally interpretable on stress ECG

structural testing

• coronary angiography (invasive) — gold standard, therapeutic option
• CT coronary angiography (CCTA) — for low-to-intermediate pre-test probability; less accurate with heavy calcification or prior stents; contraindicated in ACS

coronary artery calcium (CAC) scoring

• for asymptomatic intermediate-risk patients (FRS 10–19%) aged >40 not otherwise statin candidates
• CAC >100 → statin indicated regardless of FRS
• not a diagnostic test for symptomatic patients

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absolute contraindications to exercise stress testing

Mnemonic: I DO NOT STRESS

Letter	Contraindication
I	inflammation (myocarditis, pericarditis)
D	dissection (aortic)
O	ongoing angina
N	no consent
O	ongoing MI (within 2 days)
T	thrombosis (acute PE/DVT)
S	severe AS (symptomatic)
T	technical issues / physical limitations
R	rhythm (uncontrolled haemodynamically significant arrhythmia)
E	endocarditis (active)
S	systolic dysfunction (decompensated HF)
S	slow (physical limitations)

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high-risk features on exercise stress testing

• Duke Treadmill Score ≤ −11
• <5 METs achieved
• ST elevation or severe ST depression ≥2 mm
• ischaemia on ≥5 leads or persisting ≥3 min into recovery
• abnormal BP response: failure to reach SBP >120, drop >10 mmHg, or drop below baseline
• ventricular arrhythmia

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pharmacologic vasodilator stress — key points

• mechanism: vasodilation of normal coronary arteries reveals perfusion mismatch in territories supplied by diseased vessels (coronary steal)
• false negatives: caffeine/theophylline (must hold before test), balanced triple-vessel or left main disease
• contraindicated: high-grade AV block, active/severe asthma or COPD
• reversal agent: aminophylline

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management of chronic stable CAD

disease-modifying therapies (all patients)

• ASA + statin — backbone for all coronary atherosclerosis
• clopidogrel if ASA intolerant — CAPRIE (1996)
• ACEi if HTN, T2DM, LVEF <40%, or CKD
• beta-blocker if LVEF <40% (no MACE reduction if no prior MI and LVEF >50% — ACC/AHA 2023)
• SGLT2 Inhibitors or GLP-1RA if CAD + diabetes

antianginal therapies (symptom relief)

Class	Notes
beta-blockers	reduce HR and contractility — first-line antianginal
CCBs (non-DHP)	verapamil, diltiazem — caution if LVEF <40%
CCBs (DHP)	amlodipine — safe with reduced EF
nitrates	venodilate, reduce LVEDP — symptom relief only

lifestyle and adjunctive

• smoking cessation — counselling + pharmacotherapy together more effective than either alone
• cardiac rehab (class I-A post-MI/PCI/CABG; class I-B stable CAD)
• exercise: ≥150 min/wk aerobic + 2 days/wk resistance
• vaccines: annual influenza (I-C), COVID (I-C), pneumococcal (II-a)

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revascularisation

OMT is non-inferior to revascularisation for most stable CAD — COURAGE (2007), ORBITA (2018), ISCHEMIA (2020).

when CABG offers survival benefit over medical therapy or PCI

Scenario	Benefit of CABG
left main >50% stenosis	survival benefit over GDMT alone
multivessel disease + LVEF ≤35%	survival benefit over PCI
left main with high-complexity CAD	survival benefit + less repeat revascularisation vs PCI
multivessel + diabetes + LAD involvement	survival benefit + less repeat revascularisation vs PCI

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key trials summary

Trial	Year	Key finding
COURAGE (2007)	2007	PCI + OMT no better than OMT alone for death/MI in stable CAD
ORBITA (2018)	2018	PCI did not improve exercise time vs sham procedure in stable angina
ISCHEMIA (2020)	2020	Invasive strategy did not reduce death/MI vs conservative in moderate-severe ischaemia
CAPRIE (1996)	1996	Clopidogrel modestly superior to ASA in atherosclerotic vascular disease