Diagnostic Criteria for Chronic Coronary Syndrome
Chronic coronary syndrome (CCS) is diagnosed through a systematic approach combining clinical assessment with objective testing, where the diagnosis requires documentation of obstructive coronary artery disease (CAD) or myocardial ischemia in symptomatic patients using non-invasive functional imaging, coronary computed tomography angiography (CTA), or invasive coronary angiography. 1
Clinical Scenarios Defining CCS
CCS encompasses six distinct clinical presentations that require diagnostic evaluation 1, 2:
- Suspected CAD with stable anginal symptoms or anginal equivalents (dyspnea, exercise intolerance) 1, 3
- New onset heart failure or left ventricular dysfunction with suspected CAD 1
- Asymptomatic or symptomatic patients less than 1 year after acute coronary syndrome or recent revascularization 1
- Asymptomatic or symptomatic patients more than 1 year after initial diagnosis or revascularization 1
- Patients with angina and suspected vasospastic or microvascular disease 1
- Asymptomatic subjects in whom CAD is detected at screening 1
Initial Clinical Assessment
Risk Factor-Weighted Clinical Likelihood (RF-CL)
The diagnostic pathway begins with estimating pre-test probability using the RF-CL model, which incorporates 1, 4:
- Age and sex (women age 30-80, men age 30-80) 1
- Symptom characteristics scored 0-3 points based on typicality of angina 1
- Cardiovascular risk factors including smoking, hyperlipidemia, diabetes mellitus, hypertension, and family history of premature CAD 1, 3
This generates a clinical likelihood categorized as: very low (≤5%), low (>5-15%), moderate (>15-50%), high (>50-85%), or very high (>85%) 1, 4
Mandatory Initial Tests
- Resting 12-lead ECG to identify conduction abnormalities, prior MI, or ST-segment changes 1, 5
- Resting transthoracic echocardiography to exclude alternative causes of angina, identify regional wall motion abnormalities suggestive of CAD, measure left ventricular ejection fraction (LVEF) for risk stratification, and evaluate diastolic function 1, 5
- Basic biochemistry including full blood count, creatinine, lipid profile, and diabetes screening 5
- Chest X-ray for patients with atypical presentation, heart failure signs, or suspected pulmonary disease 1, 5
Diagnostic Testing Algorithm Based on Clinical Likelihood
Very Low Likelihood (≤5%)
Defer further diagnostic testing and manage clinically 1, 4
Low Likelihood (>5-15%)
Consider coronary artery calcium score (CACS) to reclassify patients 1:
- If CACS = 0, reclassify to very low likelihood and defer testing 1
- If CACS ≥1, proceed with diagnostic testing based on reclassified likelihood 1
Moderate Likelihood (>15-50%)
Non-invasive functional imaging for myocardial ischemia or coronary CTA is the recommended initial test 1, 4:
- Coronary CTA is preferred to rule out obstructive CAD in this probability range 4, 6
- Functional imaging (stress echocardiography, SPECT, PET, or stress cardiac magnetic resonance) is recommended if CTA shows CAD of uncertain functional significance or is non-diagnostic 1, 4
- Selection depends on clinical likelihood, patient characteristics (body habitus, ability to exercise, heart rate control), local expertise, and test availability 1
Important contraindications to coronary CTA 1:
- Extensive coronary calcification
- Irregular heart rate or uncontrolled atrial fibrillation
- Significant obesity
- Inability to cooperate with breath-hold commands
High Likelihood (>50-85%)
Stress imaging tests (SPECT, PET, stress CMR, or stress echocardiography) are recommended to diagnose and quantify myocardial ischemia 4, 6
Invasive coronary angiography (ICA) is recommended as an alternative in patients with 1:
- High clinical likelihood AND severe symptoms refractory to medical therapy
- Typical angina at low exercise level AND clinical evaluation indicating high event risk
Very High Likelihood (>85%)
Invasive coronary angiography is the recommended initial test 1, 4
Diagnostic Criteria for Obstructive CAD
Obstructive CAD is defined as 1:
- Anatomically: Coronary stenosis >90% diameter on angiography or CTA 1
- Functionally: Coronary stenosis 50-90% diameter with fractional flow reserve (FFR) ≤0.80 or instantaneous wave-free ratio (iwFR/iFR) ≤0.89 1
Invasive functional assessment (FFR/iwFR) must be available and used to evaluate stenoses before revascularization, unless very high grade (>90% diameter stenosis) 1
Additional Diagnostic Considerations
Exercise ECG
Exercise ECG is recommended for assessment of exercise tolerance, symptoms, arrhythmias, blood pressure response, and event risk in selected patients, but has lower diagnostic accuracy than imaging modalities 1, 5, 6
Vasospastic Angina
For patients with characteristic episodic resting angina and ST-segment changes that resolve with nitrates and/or calcium antagonists 1:
- ECG during angina is recommended if possible 1
- Invasive angiography or coronary CTA to determine extent of underlying coronary disease 1
- Intracoronary acetylcholine testing during invasive angiography to provoke vasospasm 1
Microvascular Dysfunction
Invasive coronary functional testing can assess microvascular dysfunction using 1:
- Coronary flow reserve (CFR) measured by thermodilution or Doppler (abnormal if <2.0) 1
- Index of microvascular resistance (IMR) (abnormal if ≥25 U) 1
Common Pitfalls to Avoid
- Do not rely solely on resting ECG for diagnosis, as more than 50% of patients with CCS have normal resting ECG 3
- Do not use coronary calcium scoring alone to identify obstructive CAD—it is useful for reclassification but not diagnosis 1, 3
- Do not perform ICA solely for risk stratification without prior non-invasive testing in stable patients 1
- Do not routinely use ambulatory ECG monitoring in initial diagnostic management unless arrhythmias are suspected 1
- Avoid stress testing in severe valvular heart disease due to low diagnostic yield and potential risks 1
Risk Stratification After Diagnosis
Once CCS is diagnosed, risk stratification is mandatory and should be based on 1, 5: