Cardiology · Ischemic Heart Disease
The facts most likely to be tested
Stable angina is defined as exertional chest pain that is predictably relieved by rest or sublingual nitroglycerin.
The primary pathophysiology is fixed coronary artery stenosis resulting in a supply-demand mismatch during periods of increased myocardial oxygen demand.
First-line pharmacotherapy for symptom control and mortality benefit is beta-blockers, which decrease heart rate and myocardial contractility.
Exercise stress testing is the initial diagnostic modality of choice for patients with a normal baseline ECG and the ability to exercise.
Pharmacologic stress testing with adenosine, dipyridamole, or regadenoson is indicated for patients who cannot achieve target heart rate via exercise.
Coronary angiography remains the gold standard for definitive diagnosis and anatomical assessment of coronary artery disease.
All patients with stable angina require secondary prevention with aspirin and a high-intensity statin to reduce the risk of future cardiovascular events.
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A 62-year-old male with a history of hypertension and hyperlipidemia presents to the clinic complaining of substernal chest pressure that occurs when he walks his dog. The pain typically lasts 5 minutes and resolves completely after he sits down to rest. His physical examination is unremarkable, and his baseline ECG shows no ST-segment changes or Q waves. He has no history of prior myocardial infarction.
What is the most appropriate initial diagnostic test to confirm the suspected diagnosis?
Exercise stress testing
The patient's presentation of predictable, exertional chest pain is classic for stable angina, and because he has a normal baseline ECG and can exercise, an exercise stress test is the preferred initial diagnostic modality.
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Etiology / Epidemiology
Caused by atherosclerotic coronary artery disease limiting blood flow during exertion. Primary risk factors: HTN, DM, smoking, dyslipidemia.
Clinical Manifestations
Predictable chest pain relieved by rest or nitroglycerin. Levine sign is the pathognomonic physical finding.
Diagnosis
Coronary angiography is the gold standard. Stress testing is the initial diagnostic choice for symptomatic patients.
Treatment
Beta-blockers are first-line. Avoid beta-blockers in Prinzmetal angina; use nitrates instead.
Prognosis
Risk of progression to ACS. Smoking cessation and statin therapy are critical for mortality reduction.
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Epidemiology & Etiology
Prevalence increases with age, particularly in males >45 and females >55. Atherosclerosis is the underlying etiology in >90% of cases. Key modifiable risk factors include diabetes mellitus, hypertension, and tobacco use.
Pertinent Anatomy
Obstruction typically occurs in the epicardial coronary arteries. Significant stenosis is defined as >70% luminal narrowing of a major vessel, which limits myocardial oxygen supply during increased demand.
Pathophysiology
Myocardial ischemia occurs when oxygen demand exceeds supply due to fixed coronary stenosis. This triggers anaerobic metabolism, leading to the accumulation of lactic acid and adenosine, which stimulate cardiac nociceptors. The process is transient and reversible, distinguishing it from the permanent necrosis seen in myocardial infarction.
Clinical Manifestations
Patients report substernal chest pressure or squeezing, often described by the Levine sign (clenched fist over the sternum). Symptoms are reliably triggered by physical exertion or emotional stress and resolve within 5-15 minutes of rest. Red flags include pain at rest or increasing frequency, which suggests progression to unstable angina.
Diagnosis
The initial test of choice is an exercise stress test to evaluate for ST-segment depression. Coronary angiography remains the gold standard for definitive anatomical diagnosis. A calcium score via CT may be used for risk stratification in asymptomatic patients.
Treatment
First-line therapy is beta-blockers to reduce myocardial oxygen demand. Sublingual nitroglycerin is used for acute symptom relief. Contraindications for nitrates include concurrent use of phosphodiesterase-5 inhibitors due to risk of severe hypotension. Long-term management requires aspirin and high-intensity statins.
Prognosis
Prognosis is determined by the number of vessels involved and left ventricular ejection fraction. Smoking cessation is the single most effective lifestyle intervention to improve long-term outcomes.
Differential Diagnosis
Unstable Angina: pain occurs at rest or with minimal exertion
Prinzmetal Angina: transient ST-elevation due to coronary vasospasm
GERD: burning retrosternal pain often unrelated to exertion
Aortic Stenosis: exertional syncope and systolic murmur
Pericarditis: pleuritic pain relieved by leaning forward