What is the initial evaluation and treatment for a patient presenting with symptoms of angina?

Initial Evaluation and Treatment for Angina

Begin by characterizing the chest pain as typical angina, atypical angina, or non-cardiac chest pain based on three specific criteria: substernal chest discomfort of characteristic quality and duration, provocation by exertion or emotional stress, and relief by rest and/or nitroglycerin—typical angina meets all three criteria. 1, 2

Clinical Assessment

Pain Characterization:

• Determine quality, location, duration, and factors that trigger and relieve the pain 1
• Assess response to nitroglycerin 2
• Distinguish stable from unstable angina—unstable angina includes new-onset angina (within 4 weeks), changing pattern of previously stable angina, or rest angina lasting >15 minutes 3

Risk Factor Assessment:

• Evaluate for smoking, hyperlipidemia, diabetes mellitus, hypertension, family history of premature CAD, and postmenopausal status in women 1, 2
• Diabetes is particularly important as it confers high risk for macrovascular disease and concurrent hypertension and hyperlipidemia 1

Exclude Precipitating Conditions:

• Conditions increasing myocardial oxygen demand: hyperthyroidism, hyperthermia, cocaine use, aortic stenosis, severe uncontrolled hypertension 1
• Conditions decreasing oxygen supply: anemia, hypoxemia from pulmonary disease, increased blood viscosity 1
• Alternative diagnoses: pericarditis, aortic dissection, pulmonary embolism, pleuritis 1

Initial Diagnostic Testing

Obtain a resting 12-lead ECG in all patients with suspected angina 1, 2

• Look for left ventricular hypertrophy, ST-T wave changes consistent with ischemia, or Q waves indicating prior MI 1, 2
• Note that >50% of patients with chronic stable angina have normal resting ECGs 1

Laboratory Testing:

• Complete blood count, fasting glucose and HbA1c, fasting lipid profile, serum creatinine, and thyroid function tests if clinically indicated 2
• Cardiac biomarkers (troponin or CK-MB) to exclude acute myocardial injury 2

Chest X-ray:

• Particularly useful if heart failure, valvular disease, or pulmonary disease is suspected 2
• Not useful for CAD diagnosis unless these comorbidities are present 1

Risk Stratification

Estimate pretest probability of CAD based on age, sex, and pain characteristics 1

• Use established tables that stratify by age, sex, and whether pain is typical angina, atypical angina, or non-cardiac 1
• Risk factors (especially diabetes, hyperlipidemia, smoking) increase probability 1
• Categorize as low (<10-20%), intermediate, or high (>80-90%) probability 1

Assess left ventricular function in specific high-risk patients:

• Obtain echocardiography or radionuclide angiography for patients with history of MI, pathologic Q waves, symptoms/signs of heart failure, or complex ventricular arrhythmias 1, 2
• Ejection fraction is the strongest predictor of long-term survival and guides therapy selection 1
• Most patients undergoing initial angina evaluation do not routinely need echocardiography 1

Functional Testing for Intermediate-to-High Probability CAD

Exercise ECG using the Bruce protocol and Duke treadmill score should be the initial test for risk stratification in patients who can exercise and are not taking digoxin 1, 2

Duke Treadmill Score Calculation:

• Exercise time (minutes) − (5 × ST-segment deviation in mm) − 4 if angina occurs − 8 if angina is reason for stopping 1
• Score ≥5 indicates low risk (4-year survival 99%, annual mortality 0.25%) 1
• Score ≤−10 indicates high risk (4-year survival 79%, annual mortality 5%) 1

Exercise ECG is NOT recommended when these confounding factors are present on resting ECG:

• Wolff-Parkinson-White syndrome 1
• Electronically paced ventricular rhythm 1

• 1 mm ST depression at rest 1

• Complete left bundle-branch block 1
• Digoxin use 1

For patients unable to exercise or with uninterpretable ECGs, use stress imaging:

• Stress echocardiography or myocardial perfusion scintigraphy (thallium-201 or technetium-99m) 1, 2
• In patients with left bundle-branch block, use pharmacologic stress (dipyridamole or adenosine) with myocardial perfusion imaging, NOT exercise or dobutamine stress, to avoid false-positive septal defects 4
• Stress imaging has superior diagnostic performance compared to exercise ECG alone and can localize ischemia 1

Initial Medical Treatment

Immediate symptom relief:

• Sublingual nitroglycerin: one tablet dissolved under the tongue at first sign of angina, may repeat every 5 minutes up to 3 tablets in 15 minutes 5
• If pain persists after 3 tablets or is different than typical, seek prompt medical attention 5
• May be used prophylactically 5-10 minutes before activities that might precipitate angina 5

Long-term antianginal therapy:

• First-line options include beta-blockers, calcium channel blockers, and long-acting nitrates 6, 7
• Beta-blockers (e.g., metoprolol) reduce myocardial oxygen consumption and are particularly useful in patients with prior MI or heart failure 8, 7
• Calcium channel blockers (e.g., amlodipine 5-10 mg daily) are effective for chronic stable angina, increasing exercise time and reducing angina frequency 9, 7
• Second-line agents (ivabradine, ranolazine, trimetazidine, nicorandil) for patients with contraindications, intolerance, or inadequate symptom control with first-line agents 6, 7

Direct Coronary Angiography Indications

Refer directly for angiography in these high-risk situations:

• Survivors of sudden cardiac death 1, 2
• Congestive heart failure 1, 2
• Severe symptoms (CCS class III-IV) despite maximal medical therapy 2
• High-risk features on non-invasive testing 2
• Special occupational requirements 1

Critical Pitfalls to Avoid

Do not abruptly discontinue beta-blockers in patients with coronary artery disease—severe exacerbation of angina, MI, and ventricular arrhythmias can occur; taper over 1-2 weeks 8

Do not perform exercise ECG in patients with left bundle-branch block, as it produces false-positive septal defects and uninterpretable results; use pharmacologic stress imaging instead 4

Do not overlook the distinction between stable and unstable angina—unstable angina (new-onset, changing pattern, or rest angina >15 minutes) requires immediate hospitalization and different management 3

Do not use electron-beam CT as a screening test for CAD—it has poor specificity (39.9-49.2%) and is not recommended 1

Beta-blockers may mask hypoglycemia symptoms in diabetic patients, though dizziness and sweating typically remain 8