What is the initial diagnostic approach for patients presenting with symptoms suggestive of angina?

Initial Diagnostic Approach for Patients with Suspected Angina

The initial diagnostic approach for patients presenting with symptoms suggestive of angina should begin with a detailed assessment of cardiovascular risk factors, medical history, and symptom characteristics, followed by a resting ECG and basic laboratory tests to estimate the pre-test likelihood of obstructive coronary artery disease (CAD). 1, 2

Clinical Assessment

• A detailed assessment of symptom characteristics is essential to classify chest pain as typical angina, atypical angina, or non-cardiac chest pain 1, 2
• Typical angina meets all three criteria: substernal chest discomfort of characteristic quality and duration, provoked by exertion or emotional stress, and relieved by rest and/or nitroglycerin 1, 2
• Consider potential angina equivalents such as dyspnea, dizziness on exertion, pain in the arms, jaw, neck, or upper back, or fatigue 1
• Evaluate cardiovascular risk factors, including smoking, hyperlipidemia, diabetes mellitus, hypertension, family history of premature CAD, and postmenopausal status in women 1, 2

Initial Testing

• Perform a resting 12-lead ECG in all patients with suspected angina to look for ST-segment depression, T-wave inversions, or Q waves suggesting previous MI 2, 1
• Obtain basic laboratory tests including complete blood count, fasting blood glucose and HbA1c, fasting lipid profile, serum creatinine, and cardiac biomarkers to exclude acute myocardial injury 2, 1
• Consider high-sensitivity C-reactive protein and/or fibrinogen plasma levels 1
• Chest X-ray is particularly useful in patients with suspected heart failure, valvular disease, or pulmonary disease 2

Pre-test Probability Assessment

• It is recommended to estimate the pre-test likelihood of obstructive epicardial CAD using the Risk Factor-weighted Clinical Likelihood model 1
• Use additional clinical data (examination of peripheral arteries, resting ECG, resting echocardiography, presence of vascular calcifications on previously performed imaging) to adjust the pre-test probability estimate 1
• In patients with very low (≤5%) pre-test likelihood of obstructive CAD, further diagnostic tests may be deferred 1

Diagnostic Testing Based on Pre-test Probability

Low Pre-test Probability (>5%-15%)

• Consider coronary artery calcium scoring (CACS) to reclassify subjects and identify those with very low CACS-weighted clinical likelihood 1
• Exercise ECG and detection of atherosclerotic disease in non-coronary arteries may be considered to adjust the pre-test likelihood estimate 1

Intermediate Pre-test Probability (15%-65%)

• Exercise ECG testing is recommended as the initial test if the patient has a normal resting ECG, can exercise adequately, and is not taking medications that interfere with ECG interpretation 1, 3
• Exercise ECG provides valuable information beyond ECG changes, including workload achieved, heart rate response, blood pressure response, and symptoms 3, 4

High Pre-test Probability (66%-85%) or LVEF <50%

• Stress imaging tests (echocardiography, nuclear imaging, or MRI) are recommended as the initial diagnostic test 1, 3
• Stress imaging techniques have superior diagnostic performance compared to exercise ECG, with the ability to quantify and localize areas of ischemia 1, 3

Special Considerations

• Exercise ECG is not recommended when the following confounding factors are found on resting ECG: pre-excitation (Wolff-Parkinson-White) syndrome, electronically paced ventricular rhythm, more than 1 mm of ST depression at rest, and complete left bundle-branch block 1, 3
• For patients with left bundle-branch block or paced rhythm, pharmacologic stress perfusion imaging (dipyridamole/adenosine) is preferred 3
• Exercise ECG is less sensitive and specific in women 1
• Echocardiography is indicated for assessment of left ventricular function in patients with a history of MI, pathologic Q waves, symptoms or signs suggestive of heart failure, and patients with complex ventricular arrhythmias 1

Indications for Direct Coronary Angiography

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

Common Pitfalls to Avoid

• Failing to distinguish between stable and unstable angina, as management pathways differ significantly 2
• Overlooking comorbid conditions that may precipitate "functional" angina, such as hyperthyroidism, anemia, or severe uncontrolled hypertension 1
• Performing unnecessary repeat testing in patients with known stable CAD and no change in symptoms 2
• Neglecting to assess for non-coronary causes of chest pain that may mimic angina 2, 5

By following this systematic approach to the initial diagnostic evaluation of patients with suspected angina, clinicians can effectively risk-stratify patients and determine the appropriate diagnostic pathway to confirm or exclude obstructive coronary artery disease.