It is unclear whether coronary artery stenosis, plaque burden, and composition differ between major epicardial arteries supplying ischemic myocardial territories.

We studied 837 symptomatic patients undergoing coronary computed tomography angiography (CTA) and ¹⁵O-water positron emission tomography (PET) myocardial perfusion imaging for suspected obstructive coronary artery disease. Coronary CTA was analyzed using artificial intelligence-guided quantitative computed tomography (AI-QCT) to assess stenosis and atherosclerotic plaque characteristics. Myocardial ischemia was defined by regional PET perfusion in the left anterior descending (LAD), left circumflex (LCX), and right coronary artery (RCA) territories.

Among arteries supplying ischemic territories, the LAD exhibited significantly higher stenosis and both absolute and normalized plaque volumes compared to LCX and RCA (P < .001 for all). Multivariable logistic regression showed diameter stenosis (P = .001-.015), percent atheroma volume (PAV; P < .001), and percent noncalcified plaque volume (NCPV) (P = .001-.017) were associated with ischemia across all three arteries. Percent calcified plaque volume (CPV) was associated with ischemia only in the RCA (P = .001).

The degree of stenosis and atherosclerotic burden are significantly higher in the LAD as compared to LCX and RCA, both in epicardial coronary arteries supplying nonischemic or ischemic myocardial territories. In all the three main coronary arteries, both luminal narrowing and plaque burden are independent predictors of ischemia, where the plaque burden is mainly driven by noncalcified plaque. However, many vessels supplying ischemic territories have a relatively low degree of stenosis and plaque burden, especially in the LCX and RCA, limiting the ability of diameter stenosis and PAV to predict myocardial ischemia.