Stable Angina & Chronic CAD
Predictable chest pain with exertion, relieved by rest or nitroglycerin. Atherosclerotic plaque causing fixed stenosis. Optimize with GDMT before revascularization. Lifestyle modification is foundation.
🔍 Overview
Definition
Stable angina = predictable, reproducible chest discomfort triggered by exertion or emotional stress, lasting 2–10 min, relieved by rest or sublingual nitroglycerin. Caused by fixed coronary stenosis limiting flow during increased demand.
Risk Stratification
| Feature | Low Risk | High Risk |
|---|---|---|
| Stress test | No ischemia, good exercise capacity | Ischemia at low workload, ↓ EF with exercise, ≥ 2 mm ST depression |
| Anatomy | Single-vessel disease, normal EF | Left main, 3-vessel disease, ↓ EF |
| Symptoms | CCS Class I–II | CCS Class III–IV despite GDMT |
🚨 Management
Medical Therapy (GDMT)
- Anti-anginal: β-blockers (1st line) → CCBs (if β-blocker contraindicated) → long-acting nitrates → ranolazine
- Anti-ischemic risk reduction: Aspirin 81 mg daily, high-intensity statin, ACEi/ARB (especially if DM, HTN, HFrEF)
- Lifestyle: Smoking cessation (#1 modifiable risk factor), exercise, weight loss, Mediterranean diet, BP < 130/80, A1c < 7%
Revascularization
Based on ISCHEMIA, 2020 - no mortality benefit of routine revascularization over GDMT in stable CAD.
- PCI - symptom relief only. No mortality benefit in stable CAD (COURAGE, 2007; ORBITA, 2018; REVIVED-BCIS2, 2022).
- CABG - survival benefit in left main disease, 3-vessel disease with ↓ EF, or diabetes with multi-vessel disease (FREEDOM, 2012)
Bottom line: For stable CAD, GDMT is the foundation. Revascularization improves angina symptoms but does NOT reduce death or MI (ISCHEMIA, COURAGE, ORBITA). CABG has survival benefit only in left main, 3-vessel + reduced EF, or diabetes with multivessel disease (FREEDOM).
🧪 Workup
- ECG - may be normal at rest. ST depression during pain.
- Stress testing - exercise preferred. Pharmacologic if cannot exercise. Nuclear/echo for added anatomic info.
- Coronary CT angiography - anatomic assessment, calcium scoring
- Cardiac catheterization - if high-risk features on non-invasive testing
- Lipid panel, HbA1c, BMP, TSH
- Echo - baseline LV function
Stress Test Selection
| Test Type | When to Use | Sensitivity | Key Notes |
|---|---|---|---|
| Exercise ECG | Can exercise + interpretable ECG | ~68% | First-line, cheapest. Positive = ≥ 1mm ST depression. |
| Exercise Echo | Can exercise + uninterpretable ECG or need anatomic info | ~85% | Detects wall motion abnormalities. Better specificity than ECG alone. |
| Exercise Nuclear (SPECT) | Can exercise + need perfusion data | ~87% | Identifies ischemic territory for intervention planning. |
| Pharmacologic (Dobutamine Echo) | Cannot exercise | ~82% | Simulates exercise. Detects viable/stunned myocardium. |
| Pharmacologic (Vasodilator Nuclear) | Cannot exercise + LBBB or paced rhythm | ~90% | Adenosine/regadenoson. Preferred over dobutamine for LBBB (avoids septal artifact). |
| Coronary CTA | Low-intermediate risk, anatomy needed | ~95% | High NPV. Rules out CAD. Also gives calcium score. |
💊 Medications
| Drug | Dose | Role | Key Notes |
|---|---|---|---|
| Metoprolol Succinate (Toprol XL) | 25–200 mg daily | 1st line anti-anginal | ↓ HR → ↓ myocardial O₂ demand. Target HR 55–60. |
| Amlodipine (Norvasc) | 5–10 mg daily | 2nd line / add-on | Long-acting DHP CCB. Use if β-blocker contraindicated or vasospastic angina. |
| Isosorbide Mononitrate (Imdur) | 30–120 mg daily | Add-on anti-anginal | 10–14h nitrate-free interval required to prevent tolerance. |
| Ranolazine (Ranexa) | 500–1000 mg BID | Add-on | Late sodium current inhibitor. No hemodynamic effects. Prolongs QTc. |
| Aspirin | 81 mg daily | Antiplatelet | Lifelong. Reduces MI and CV death. |
| Atorvastatin (Lipitor) | 40–80 mg daily | High-intensity statin | Plaque stabilization + LDL reduction. Target LDL < 70. |
📋 On Rounds
Pimp Questions
What did the ISCHEMIA trial show about revascularization in stable CAD?
No reduction in death or MI with routine invasive strategy vs conservative management in patients with stable CAD and moderate-severe ischemia. Invasive strategy improved anginal symptoms more. Key takeaway: GDMT is the foundation -revascularization is for symptom control in stable disease, not mortality reduction.
When does CABG provide a survival benefit over PCI?
Left main disease (≥ 50% stenosis), 3-vessel disease with reduced EF, and diabetes with multi-vessel disease (FREEDOM trial). CABG provides more complete revascularization with better long-term outcomes in these high-risk anatomies.
Why is a nitrate-free interval important?
Continuous nitrate exposure → nitrate tolerance within 24–48h via depletion of sulfhydryl groups needed for NO generation. A 10–14 hour nitrate-free interval (usually overnight) restores sensitivity. This is why isosorbide mononitrate is dosed once daily in the morning.
What is the mechanism of ranolazine?
Late sodium current inhibitor - reduces intracellular calcium overload without hemodynamic effects (no change in HR or BP). MERLIN-TIMI 36, 2007 showed reduced recurrent ischemia but no mortality benefit. Prolongs QTc - avoid with other QT-prolonging drugs.
What did the COURAGE trial show?
PCI + GDMT was not superior to GDMT alone for death or MI in stable CAD. Optimal medical therapy is the foundation of treatment. Revascularization improves symptoms but not hard outcomes. COURAGE, 2007.
Which patients benefit from CABG over PCI in diabetes?
FREEDOM, 2012: CABG superior to PCI for death, MI, and stroke in diabetics with multivessel disease. Lower rates of repeat revascularization with CABG. Drives current guideline recommendation for surgical revascularization in this population.
What is the Canadian Cardiovascular Society (CCS) angina classification?
Class I: ordinary activity doesn't cause angina (e.g., walking, climbing stairs). Class II: slight limitation - angina with rapid walking or climbing > 1 flight. Class III: marked limitation - angina walking 1-2 blocks or 1 flight. Class IV: angina at rest or with any physical activity.
When should you choose pharmacologic vs exercise stress testing?
Pharmacologic if patient cannot exercise (orthopedic limitation, deconditioning, PAD) or has uninterpretable ECG (LBBB, paced rhythm, LVH with repolarization changes, digoxin use). Exercise preferred when possible - provides functional capacity data and is more physiologic.
What is the role of coronary calcium scoring?
CAC = 0 has excellent negative predictive value for obstructive CAD. MESA study validated its use for risk reclassification. Helps reclassify intermediate-risk patients (moves them to low or high risk). Not useful if patient already has known CAD. Obtained via non-contrast CT chest.
Clinical Examples
📋 Case 1, New Diagnosis of Stable Angina
Patient: 64M with HTN, HLD, T2DM. Exertional chest pressure with brisk walking × 3 months, relieved by rest within 5 min. Normal ECG at rest. EF 60%.
Key findings: Classic stable angina: predictable exertional chest pain, relieved by rest. Intermediate pretest probability for CAD given age, sex, and risk factors.
Management:
- Stress test for risk stratification, exercise stress echo (can exercise, interpretable ECG)
- Start ASA 81 mg + high-intensity statin (atorvastatin 80 mg)
- Metoprolol succinate 25 mg daily (first-line anti-anginal, reduces HR and O₂ demand)
- SL nitroglycerin PRN for breakthrough episodes
- If high-risk stress test (large ischemic burden, drop in BP) → coronary angiography
Teaching point: Beta-blockers are first-line for stable angina, they reduce mortality in post-MI patients and improve anginal symptoms. CCBs (amlodipine, diltiazem) are second-line or added if beta-blockers insufficient.
📋 Case 2, Refractory Angina Despite Medical Therapy
Patient: 72F with known 3-vessel CAD (declined CABG 2 years ago). Angina now occurring with minimal exertion despite metoprolol 100 mg BID, amlodipine 10 mg, isosorbide mononitrate 60 mg daily, ASA, atorvastatin. CCS class III.
Key findings: Refractory angina on maximized triple anti-anginal therapy. Previously documented 3-vessel disease. Progressive limitation despite optimal medical management.
Management:
- Add ranolazine 500 mg BID → titrate to 1000 mg BID (late sodium channel inhibitor, reduces ischemia without hemodynamic effects)
- Reassess revascularization candidacy, repeat coronary angiography
- Heart team discussion: CABG vs high-risk PCI for 3-vessel disease ISCHEMIA, 2020
- Cardiac rehab referral (improves exercise capacity and anginal threshold)
- Ensure nitrate-free interval (10-14h overnight) to prevent tolerance
Teaching point: Ranolazine is the fourth-line anti-anginal agent, it works by a unique mechanism (late Na channel) and can be added to any combination without hemodynamic interactions. No mortality benefit, but improves symptoms.
📋 Case 3, Vasospastic (Prinzmetal) Angina
Patient: 42F non-smoker, no traditional risk factors. Recurrent rest angina at 3-4 AM with transient ST elevation on telemetry that resolves spontaneously. Normal coronary angiogram.
Key findings: Classic vasospastic angina: rest pain, early morning, transient ST elevation, clean coronaries. Often triggered by smoking, cocaine, or cold exposure.
Management:
- Long-acting CCB first-line: amlodipine 5-10 mg daily or diltiazem ER 240 mg daily
- Long-acting nitrate (isosorbide mononitrate 30-60 mg daily) if CCB alone insufficient
- AVOID beta-blockers (unopposed alpha-mediated vasoconstriction can worsen spasm)
- SL nitroglycerin PRN for acute episodes
- Avoid triggers: cocaine, triptans, ergot alkaloids, cold exposure
Teaching point: Beta-blockers are contraindicated in vasospastic angina, they remove beta-2 vasodilation, leaving alpha-mediated constriction unopposed. This is the one form of angina where beta-blockers make things worse.
⚡ Summary
Define It Before You Test It
Predictable, exertional chest discomfort relieved by rest or nitroglycerin, from a fixed atherosclerotic stenosis. Any change in the pattern, at rest, more frequent, or at a lower threshold, is no longer stable angina and moves the patient onto the acute coronary syndrome pathway.
Medical Therapy Is the Foundation
Antiplatelet, high-intensity statin, blood pressure and diabetes control, plus a beta blocker as first-line antianginal. Add a calcium channel blocker or long-acting nitrate for persistent symptoms, and ranolazine when the heart rate or blood pressure will not tolerate more. The statin and antiplatelet are what change mortality; the antianginals only change how the patient feels.
The Result That Changed Practice
Revascularization improves angina but does not reduce death or myocardial infarction in stable CAD (ISCHEMIA, COURAGE, and ORBITA, where PCI did not beat a sham procedure for exercise time). So optimize medical therapy first, and offer PCI for symptoms that persist despite it, not as a reflex to an abnormal stress test.
When Revascularization Does Save Lives
CABG has a survival benefit in left main disease, three-vessel disease with reduced ejection fraction, and diabetes with multivessel disease (FREEDOM). Those are anatomic and physiologic indications, not symptomatic ones, which is why the anatomy still matters even in a patient whose angina is controlled.
Pick the Stress Test for the Patient
Can exercise with an interpretable ECG → exercise ECG, cheapest and first line. Uninterpretable ECG → add imaging with exercise echo or SPECT. Cannot exercise → pharmacologic. LBBB or a paced rhythm → vasodilator nuclear, not dobutamine, because septal motion artifact makes the echo uninterpretable. Low to intermediate risk needing anatomy → coronary CTA, which has a very high negative predictive value and rules CAD out.
Know What a High-Risk Stress Test Looks Like
Ischemia at a low workload, a fall in ejection fraction with exercise, ST depression of 2 mm or more, or a large ischemic territory. These, along with left main or three-vessel anatomy and CCS class III to IV symptoms despite medical therapy, are what push toward catheterization rather than another medication.
Lifestyle Is Not the Soft Part of the Plan
Smoking cessation is the single highest-yield intervention and reduces events more than any drug on the list. Add exercise, a Mediterranean-style diet, weight loss, and cardiac rehabilitation, which independently improves survival.
Common Pitfalls
Do not stress-test an asymptomatic patient: it finds lesions whose treatment does not help and starts a cascade. Do not treat a stenosis found on angiography without functional significance, which is what FFR or iFR is for. Do not stop the statin because the LDL looks good: the benefit is from continued treatment, not from a number reached once.
Related Topics
ACS OverviewAortic DissectionAortic StenosisArrhythmiasAtrial FibrillationCardiac Tamponade