USMLE Guide: Angina Pectoris

Introduction

Angina pectoris is a common symptom of coronary artery disease (CAD) characterized by chest pain or discomfort due to inadequate blood flow to the heart muscle. This USMLE guide provides a comprehensive overview of angina pectoris, including its pathophysiology, clinical presentation, diagnosis, and management.

Pathophysiology

Angina pectoris typically occurs due to atherosclerosis and the resultant narrowing of coronary arteries. This leads to reduced blood flow and oxygen supply to the myocardium, causing ischemia. Ischemia triggers the release of various vasoactive substances, such as adenosine, bradykinin, and prostaglandins, which stimulate sensory nerve endings in the heart, leading to angina pain.

Clinical Presentation

1. Chest Discomfort: The hallmark symptom of angina pectoris is a retrosternal or left-sided chest pain or discomfort that may radiate to the left arm, jaw, neck, or back. The pain is typically described as squeezing, pressure-like, or tightness.
2. Precipitating Factors: Angina pain is often triggered by physical exertion, emotional stress, cold weather, heavy meals, or smoking.
3. Duration: Episodes of angina usually last for a few minutes (typically 2-10 minutes) and are relieved by rest or nitroglycerin.
4. Associated Symptoms: Patients may experience dyspnea, diaphoresis, nausea, and fatigue during angina episodes.

Diagnosis

1. History and Physical Examination: A detailed history focusing on the nature, duration, and precipitating factors of chest pain, along with associated symptoms, is crucial. physical examination may reveal signs of cardiovascular disease, such as hypertension or abnormal heart sounds.
2. Electrocardiogram (ECG): Resting ECG is often the initial diagnostic test. It may show ST-segment depression or T-wave inversion during episodes of angina, indicating myocardial ischemia.
3. Exercise Stress Test: In patients with a normal resting ECG, an exercise stress test (treadmill or pharmacological) helps to provoke angina and detect ECG changes suggestive of myocardial ischemia.
4. Cardiac Imaging: If the stress test is inconclusive or high-risk, additional imaging such as stress echocardiography or nuclear imaging (e.g., myocardial perfusion scan) may be performed to assess for areas of reversible ischemia.
5. Coronary Angiography: Invasive coronary angiography is the gold standard for visualizing coronary artery stenosis and determining the need for revascularization procedures (e.g., percutaneous coronary intervention or coronary artery bypass grafting).

Management

The management of angina pectoris involves both non-pharmacological and pharmacological interventions.

Non-pharmacological

1. Lifestyle Modifications: Encourage patients to adopt a heart-healthy lifestyle, including smoking cessation, regular exercise, healthy diet, weight management, and stress reduction.
2. Cardiac Rehabilitation: Refer patients to a cardiac rehabilitation program to improve exercise tolerance, reduce risk factors, and enhance overall cardiovascular health.

Pharmacological

1. Nitroglycerin: Sublingual nitroglycerin is the first-line treatment for acute angina episodes, providing rapid relief by causing coronary vasodilation.
2. Beta-Blockers: These medications reduce heart rate, myocardial contractility, and blood pressure, thus decreasing myocardial oxygen demand. They are the cornerstone of chronic stable angina management.
3. Calcium Channel Blockers: These agents reduce myocardial oxygen demand by causing arterial vasodilation and reducing afterload. They are particularly useful in patients with contraindications or intolerances to beta-blockers.
4. Aspirin: Long-term aspirin therapy is essential to reduce the risk of cardiovascular events in patients with angina, as it inhibits platelet aggregation.
5. Statins: These lipid-lowering agents are recommended in patients with angina to reduce LDL cholesterol levels and stabilize atherosclerotic plaques, thereby preventing further cardiovascular events.

Conclusion

Angina pectoris is a common manifestation of coronary artery disease and requires prompt recognition and management. This USMLE guide has provided an overview of its pathophysiology, clinical presentation, diagnosis, and management, including both non-pharmacological and pharmacological approaches. Understanding these key concepts will help healthcare professionals effectively evaluate and treat patients with angina pectoris.