Does she need a coronary angiography (CAG)?

Coronary Angiography (CAG) Indications

Coronary angiography (CAG) is indicated for this patient if she has significant coronary artery disease risk factors, symptoms suggesting ischemia, or if she is being evaluated for cardiac surgery. 1, 2

Decision Algorithm for CAG

Class I Indications (Definite Need for CAG):

• Patients with significant left main coronary artery stenosis
• Patients with left main equivalent disease (≥70% stenosis of proximal LAD and proximal left circumflex)
• Patients with 3-vessel disease
• Patients with 2-vessel disease with significant proximal LAD stenosis and either EF <0.50 or demonstrable ischemia on noninvasive testing
• Patients undergoing valve surgery who are at risk for CAD
• Patients with unstable angina/non-ST elevation MI with significant left main or left main equivalent disease

Class IIa Indications (Reasonable to Perform CAG):

• Patients with stable angina who have proximal LAD stenosis with 1-vessel disease
• Patients with unstable angina/non-ST elevation MI who have proximal LAD stenosis with 1- or 2-vessel disease

Class III Indications (CAG Not Recommended):

• Patients with 1- or 2-vessel disease not involving significant proximal LAD stenosis with mild symptoms unlikely due to myocardial ischemia
• Patients with borderline coronary stenoses (50-60% diameter) and no demonstrable ischemia
• Patients with insignificant coronary stenosis (<50% diameter reduction)

Special Considerations

Pre-Cardiac Surgery Evaluation

CAG is strongly recommended before valve replacement surgery in patients at risk for CAD 2. The ACC/AHA guidelines specifically state that "coronary angiography is recommended before AVR in patients with AS at risk for CAD" (Level of Evidence: B) 2. This is critical because:

1. Undiagnosed CAD can negatively impact both perioperative and late outcomes of valve surgery 2
2. Concomitant CABG at the time of valve surgery has been shown to reduce perioperative myocardial infarction rates 2
3. Incomplete revascularization is associated with greater post-operative LV systolic dysfunction and reduced survival 2

Left Ventricular Dysfunction

If the patient has left ventricular dysfunction, CAG becomes even more important as:

• LV dysfunction has been shown to be significantly related to ongoing myocardial ischemia, hibernation, and coronary artery disease 3
• CAG remains the gold standard for determining revascularization decisions in patients with LV dysfunction 3
• The presence of coronary stenosis on CAG in patients with heart failure is associated with worse prognosis 4

Alternative Imaging Considerations

While CAG remains the gold standard for evaluating coronary artery disease 5, contrast-enhanced coronary CT angiography may be considered as an alternative in selected patients who are at low to intermediate pretest probability of CAD 2. However:

• CT angiography is not appropriate for patients with active angina symptoms, documented ischemia, or prior history of CAD 2
• A positive CT angiogram still requires confirmation with invasive CAG to establish the need for and extent of CABG 2

Common Pitfalls and Caveats

1. Don't delay CAG in high-risk patients: Delaying CAG in patients with significant symptoms or high-risk features can lead to missed opportunities for timely revascularization.

2. Consider functional assessment: Modern CAG can be complemented with physiological assessment methods to evaluate the functional significance of coronary lesions 6.

3. Don't perform unnecessary CAG: In patients with low probability of CAD, mild symptoms, or those unlikely to benefit from revascularization, CAG may expose patients to unnecessary risks.

4. Remember that CAG findings impact surgical planning: For patients undergoing valve surgery, knowledge of coronary anatomy is essential for comprehensive surgical planning and may influence the surgical approach 2.

In summary, the decision to perform CAG should be based on the patient's clinical presentation, risk factors for CAD, planned cardiac interventions, and potential benefit from revascularization. For patients being evaluated for cardiac surgery, particularly valve surgery, CAG is strongly recommended to identify concomitant CAD that would benefit from surgical revascularization.