What diagnostic tests are necessary for a patient with stable angina?

Diagnostic Tests for Patients with Stable Angina

For patients with stable angina, essential diagnostic tests include standard laboratory biochemical testing, resting ECG, echocardiography, exercise stress testing, and in selected cases, stress imaging studies and coronary angiography. 1

Initial Basic Testing (First-line)

• Complete blood count including hemoglobin and white cell count to identify possible causes of ischemia and provide prognostic information 1
• Fasting plasma glucose and HbA1c to screen for diabetes, with oral glucose tolerance test if results are inconclusive 1
• Creatinine measurement and estimation of renal function (creatinine clearance) 1
• Lipid profile including total cholesterol, HDL, LDL, and triglycerides 1
• Thyroid function tests if clinically indicated 1
• Resting 12-lead ECG to identify evidence of prior MI, left ventricular hypertrophy, conduction abnormalities, or ischemic changes 1
• Resting echocardiography to assess left ventricular function, wall motion abnormalities, and valvular disease 1
• Chest X-ray only in patients with suspected heart failure or significant pulmonary disease 1

Non-invasive Cardiac Investigations

Exercise ECG Testing

• First-line stress test for most patients with new-onset stable angina who can exercise 1, 2
• Provides information on exercise capacity, hemodynamic response, and presence of exercise-induced ischemia 1
• Should be terminated for symptom limitation, significant ST changes (>2mm depression or 1mm elevation), significant arrhythmias, or marked blood pressure changes 1

When to Use Stress Imaging Instead of Exercise ECG

• Patients with resting ECG abnormalities that interfere with interpretation (ST depression >1mm, complete left bundle-branch block, ventricular paced rhythm, or preexcitation syndrome) 2
• Patients with previous revascularization (PCI or CABG) 2
• Patients unable to exercise adequately 1, 2
• When exercise ECG results are equivocal or intermediate-risk 1

Types of Stress Imaging

• Stress echocardiography - evaluates wall motion abnormalities during stress 1
• Myocardial perfusion imaging (nuclear) - assesses perfusion defects during stress 1
• Pharmacological stress can be used for patients unable to exercise 2

Risk Stratification

• Low-risk patients (estimated annual mortality <1%): can begin medical therapy without further testing 2
• Intermediate-risk patients (estimated annual mortality 1-3%): should undergo stress imaging or coronary angiography 2
• High-risk patients (estimated annual mortality >3%): should undergo coronary angiography 2

Indications for Coronary Angiography

• Severe symptoms (Canadian Cardiovascular Society class III) despite maximal medical therapy 1
• High-risk findings on non-invasive testing 2
• Known left ventricular dysfunction 2
• Patients with unstable symptoms or clinical instability 1, 3
• Special occupational requirements 1

Follow-up Testing

• Annual fasting lipid profile and fasting glucose 1
• Repeat ECG when medications affecting cardiac conduction are changed or when anginal pattern changes 1
• Repeat stress testing only if significant change in clinical status (not routinely recommended more frequently than every 3 years in stable patients) 1
• Repeat echocardiography if new or worsening heart failure or valvular disease 1

Common Pitfalls to Avoid

• Overinterpreting nonspecific ST-T wave changes as definitive evidence of ischemia 4
• Failing to consider medication effects as potential causes of ECG changes 4
• Overuse of repeated stress testing in patients with stable symptoms 1
• Underestimating the prognostic value of exercise capacity in risk assessment 5
• Not considering microvascular angina in patients with typical symptoms but normal coronary arteries 1