In symptomatic patients with concern for obstructive CAD, CCTA is preferred under which circumstance?

• A. High clinical likelihood of CAD
• B. No history of CAD
• C. Low clinical likelihood of CAD
• D. Younger patient, non-obese

Answer: (C)

The main idea is using imaging tests based on pretest probability. CCTA is most helpful to rule out obstructive CAD when the likelihood of disease is low. In patients with symptoms but a low pretest probability, CCTA has a high negative predictive value, so a normal result effectively excludes obstructive CAD and can spare the patient from invasive angiography. This makes it the preferred noninvasive test in that setting. In contrast, if the probability of CAD is high, invasive coronary angiography is more informative because CCTA may be less decisive due to calcification or other factors, and you want definitive anatomy. Age or obesity can affect image quality, but they don’t by themselves determine the test choice as strongly as the estimated probability of disease. So the best scenario for preferring CCTA is when the clinical likelihood of CAD is low.