What are the different classes of angina and their respective treatments?

Classification of Angina

Angina is classified using the Canadian Cardiovascular Society (CCS) grading system, which stratifies patients into four classes based on the level of physical activity that precipitates symptoms, with Class I representing minimal limitation and Class IV representing symptoms at rest. 1

Canadian Cardiovascular Society (CCS) Classification System

The CCS classification provides a standardized framework for grading stable angina severity:

• Class I: Angina occurs only with strenuous, rapid, or prolonged exertion at work or recreation. Ordinary physical activity such as walking or climbing stairs does not cause angina. 1

• Class II: Slight limitation of ordinary activity. Angina occurs when walking or climbing stairs rapidly, walking uphill, walking or climbing stairs after meals, in cold weather, in wind, under emotional stress, or only during the few hours after awakening. Angina occurs on walking more than 2 blocks on level ground and climbing more than 1 flight of ordinary stairs at a normal pace under normal conditions. 1

• Class III: Marked limitation of ordinary physical activity. Angina occurs on walking 1 to 2 blocks on level ground and climbing 1 flight of stairs under normal conditions at a normal pace. 1

• Class IV: Inability to perform any physical activity without discomfort—anginal symptoms may be present at rest. 1

Clinical Types of Angina

Beyond the CCS functional classification, angina is categorized by clinical presentation:

Stable Angina

Angina without a change in frequency or pattern for at least 6 weeks. The pain is controlled by rest and/or sublingual/oral/transdermal medications. 1

Unstable Angina

Unstable angina represents a medical emergency requiring immediate hospitalization and has three principal presentations: 1, 2

• Rest angina: Angina occurring at rest and prolonged, usually lasting more than 20 minutes 1, 2

• New-onset severe angina: New-onset angina of at least CCS Class III severity within 2 months of presentation 1, 2

• Crescendo angina: Previously diagnosed angina that has become distinctly more frequent, longer in duration, or lower in threshold—increased by at least 1 CCS class to at least CCS Class III severity 1, 2

Variant (Prinzmetal) Angina

Angina that usually occurs spontaneously at rest and does not require physical exertion. It is frequently associated with transient ST-segment elevation and is caused by coronary vasospasm. 1

Atypical Chest Pain

Pain, pressure, or discomfort in the chest, neck, or arms not clearly exertional or not otherwise consistent with pain or discomfort of myocardial ischemic origin. 1

Microvascular Angina (Syndrome X)

Typical exercise-induced angina with positive stress testing but normal coronary arteries on angiography, often associated with endothelial dysfunction. 1, 3

Treatment Approach by Angina Type

Stable Angina (CCS Class I-IV)

First-line pharmacologic therapy includes:

• Beta-blockers (e.g., metoprolol): Reduce heart rate, myocardial contractility, and oxygen demand. 4, 5, 6
• Calcium channel blockers (e.g., diltiazem 180-360 mg/day): Particularly effective for vasospastic angina. 4, 6
• Short-acting nitrates: For acute symptom relief. 4, 6

Second-line agents (when first-line contraindicated, not tolerated, or inadequate):

• Ranolazine, ivabradine, nicorandil, trimetazidine 6

Revascularization indications: 1, 3

• PCI: Indicated for CCS Class I-IV angina despite medical therapy with suitable single-vessel disease
• CABG: Indicated for left main disease, three-vessel disease with large ischemia, three-vessel disease with poor ventricular function, or two-to-three vessel disease including severe proximal LAD disease

Unstable Angina

Immediate management requires: 2, 7

• Immediate hospitalization with continuous ECG monitoring
• Aspirin 75-325 mg/day
• Anticoagulation with unfractionated heparin or enoxaparin
• Nitrates for symptom relief
• Early risk stratification using clinical criteria, ECG changes, and cardiac biomarkers

Invasive strategy: 2

• Early coronary angiography within 24-48 hours for high-risk patients
• PCI with dual antiplatelet therapy for suitable anatomy
• CABG preferred for diabetic patients with multivessel disease

Variant Angina

Calcium channel blockers are primary therapy rather than beta-blockers, which may worsen coronary vasospasm. 3, 4

Microvascular Angina

Consider assessment for endothelial dysfunction; treatment focuses on risk factor modification and may include calcium channel blockers or ACE inhibitors. 3

Common Pitfalls

• Atypical presentations are more common in elderly patients, women, and those with diabetes, chronic kidney disease, or dementia—maintain high clinical suspicion. 1
• Normal ECG does not exclude unstable angina—approximately 5% of patients with unstable angina have completely normal ECG even during symptoms. 7
• Women may have non-obstructive coronary disease despite typical angina symptoms—consider microvascular dysfunction. 7
• Beta-blockers may worsen vasospastic angina—use calcium channel blockers instead. 3
• High-sensitivity troponin assays have decreased the diagnosis of unstable angina by reclassifying many patients as NSTEMI, but unstable angina patients have substantially lower mortality risk. 1