What is Angina?
Angina is chest pain or discomfort caused by insufficient blood supply to the heart muscle (myocardial ischemia), typically due to coronary artery disease. 1
Clinical Characteristics
Anginal pain has specific features that distinguish it from other types of chest pain:
Location and Quality: The pain is typically substernal (under the breastbone), described as pressure, tightness, squeezing, or heaviness rather than sharp pain. 1
Radiation Pattern: Pain commonly radiates to the neck, jaw, epigastrium, shoulders, or arms (particularly the left arm). 1
Duration: Episodes typically last minutes, not seconds or hours. 1
Triggers: Pain is characteristically provoked by physical exertion or emotional stress and relieved by rest. 1
Response to Nitroglycerin: Sublingual nitroglycerin usually relieves angina within 30 seconds to several minutes. 1, 2
Classification of Chest Pain
The American College of Cardiology/American Heart Association guidelines classify chest pain into three categories based on these characteristics: 1
Typical Angina: Meets all three criteria - (1) substernal chest discomfort with characteristic quality and duration, (2) provoked by exertion or emotional stress, and (3) relieved by rest or nitroglycerin. 1
Atypical Angina: Meets only two of the above characteristics. 1
Noncardiac Chest Pain: Meets one or none of the typical anginal characteristics. 1
Important Variations in Presentation
Not all patients describe classic symptoms:
Women and elderly patients often present with atypical symptoms including sharp pain, nausea, vomiting, or midepigastric discomfort rather than typical chest pressure. 1
Many patients describe their discomfort as "tightness" or "pressure" rather than frank pain. 1
Stable vs. Unstable Angina
Patients presenting with angina must be immediately categorized as stable or unstable, as this determines urgency of management. 1
Stable Angina: Predictable pattern of chest pain with exertion, relieved by rest, without recent change in frequency or severity. 1
Unstable Angina (UA): Defined as (1) new-onset angina within 2 months, (2) increasing angina (more frequent, longer duration, or lower threshold), or (3) angina occurring at rest lasting >20 minutes. 1
Patients with unstable angina at high or moderate risk require immediate emergency department transfer, as they may have experienced coronary plaque rupture with risk of myocardial infarction or death. 1
Special Consideration: Hypertension and Angina
In patients with hypertension, angina can occur through multiple mechanisms beyond typical coronary artery disease:
Severe uncontrolled hypertension increases left ventricular wall tension, raising myocardial oxygen demand while simultaneously decreasing subendocardial perfusion. 1
Coronary microvascular disease can cause angina in hypertensive patients even without epicardial coronary artery disease or left ventricular hypertrophy, due to abnormally elevated resistance in the coronary microvasculature. 3
Hypertension is a major risk factor that increases the likelihood of underlying coronary artery disease when angina is present. 1
Underlying Pathophysiology
Angina results from an imbalance between myocardial oxygen supply and demand:
Ischemia occurs when oxygen delivery is insufficient for metabolic needs, causing cells to switch to anaerobic metabolism and release lactic acid. 4
This metabolic shift activates sensory neurons in the heart, producing the sensation of anginal pain. 4
Critical Clinical Pitfall
Pain location above the mandible, below the epigastrium, or localized to a small area over the left lateral chest wall is rarely angina. 1 However, pain reproducible by chest wall palpation suggests musculoskeletal origin but does not eliminate the possibility of cardiac ischemia. 1