What are the different types of angina?

Types of Angina

Angina is classified into five major types: stable angina, unstable angina, variant (Prinzmetal's) angina, atypical angina, and microvascular angina (Syndrome X), each with distinct clinical presentations and prognostic implications that guide management decisions. 1

Stable Angina

Stable angina is characterized by predictable chest discomfort that occurs with exertion or emotional stress, has not changed in frequency or pattern for at least 6 weeks, and is consistently relieved by rest and/or nitroglycerin. 1

• The discomfort is typically retrosternal, described as pressure or heaviness, and may radiate to the left arm, neck, or jaw 1
• Episodes are triggered by increased myocardial oxygen demand (physical activity, emotional stress) and resolve within minutes of rest 1, 2
• Severity is graded using the Canadian Cardiovascular Society (CCS) classification system from Class I (angina only with strenuous exertion) to Class IV (inability to perform any activity without discomfort, symptoms at rest) 1

Unstable Angina

Unstable angina represents a critical phase of coronary disease with three defining presentations: rest angina lasting ≥20 minutes, new-onset severe angina (CCS Class III or IV), or crescendo angina with recent acceleration in severity. 1, 3

• This is a high-risk condition that lies between stable angina and myocardial infarction, requiring urgent evaluation 3, 4
• Unlike stable angina, symptoms occur unpredictably at rest or with minimal exertion 3
• Compared to NSTEMI patients, those with unstable angina have lower mortality risk but still face substantial morbidity 1, 3
• Critical pitfall: Approximately 5% of patients may have completely normal ECG even during symptoms, and some patients (particularly women) may have non-obstructive coronary disease on angiography 3

Variant (Prinzmetal's) Angina

Variant angina is caused by coronary artery vasospasm, typically occurs spontaneously at rest (not with exertion), and is characterized by transient ST-segment elevation during episodes. 1, 5

• This form predominantly affects younger women who may lack traditional cardiovascular risk factors except cigarette smoking 5
• Episodes occur at rest, often in the early morning hours, and are associated with vasospastic disorders like Raynaud's phenomenon or migraine headaches 1, 5
• The diagnosis requires observing transient ST-segment elevation during anginal attacks; exercise stress testing is not useful since this is a supply (vasospasm) rather than demand problem 5
• Critical management distinction: Beta-blockers and high-dose aspirin are contraindicated in variant angina, while calcium channel blockers and nitrates are the mainstay of therapy 5

Atypical Angina

Atypical angina refers to chest discomfort that is possibly consistent with myocardial ischemia but lacks the classic characteristics of typical angina pectoris. 1

• Symptoms may include epigastric pain, indigestion-like complaints, or isolated dyspnea without classic chest pressure 1
• This presentation is more common in elderly patients, women, and those with diabetes, chronic kidney disease, or dementia 1
• The pain may not follow the typical pattern of exertional provocation and rest relief 1

Microvascular Angina (Cardiac Syndrome X)

Microvascular angina (Syndrome X) is defined by the triad of typical exercise-induced angina, positive stress testing, and angiographically normal coronary arteries, caused by coronary microvascular dysfunction. 1

• Patients experience frequent anginal episodes (often several times per week) with both exertional and resting chest pain 1
• This condition is frequently encountered in patients with hypertension, with or without left ventricular hypertrophy 1
• Prognostic consideration: While mortality is generally favorable, morbidity is high with continuing chest pain episodes and frequent hospital readmissions 1
• Emerging evidence suggests that endothelial dysfunction in this population may identify patients at risk for future atherosclerotic disease development 1

Noncardiac Chest Pain

Noncardiac chest pain represents discomfort that is inconsistent with myocardial ischemia and requires consideration of alternative diagnoses including gastrointestinal, pulmonary, or musculoskeletal causes. 1

• Differential diagnoses include esophageal spasm, gastric ulcer, cholecystitis, pancreatitis, pulmonary embolism, pericarditis, and aortic dissection 1
• Pain reproduced by chest wall palpation suggests musculoskeletal origin 1

Clinical Decision-Making Algorithm

When evaluating chest pain, follow this sequence:

1. First, determine stability: Does the pain occur predictably with exertion and resolve with rest (stable), or does it occur at rest/with minimal exertion or show recent acceleration (unstable)? 1, 3

2. Second, assess timing and triggers: Does pain occur exclusively at rest, particularly in early morning (suggests variant angina), or primarily with exertion (stable or microvascular angina)? 1, 5

3. Third, evaluate response to testing: If stress testing is positive but angiography shows normal coronaries, consider microvascular angina 1

4. Fourth, identify high-risk features: Prolonged rest pain ≥20 minutes, new severe symptoms, or accelerating pattern mandate urgent evaluation for unstable angina/acute coronary syndrome 3

Common pitfall: Relief of symptoms with nitroglycerin is not specific for angina, as it occurs with other causes of chest pain including esophageal disorders 1