Purpose: To evaluate whether assessment of total coronary artery plaque volume by coronary computed tomography angiography (CCTA) in patients with non-obstructive CAD could identify those with myocardial ischemia.
Methods: We studied 129 patients (mean age 62 ± 8 years, 56% women) with angina pectoris and non-obstructive CAD (stenosis <50%) by CCTA included in the Myocardial ischemia in non-obstructive coronary artery disease (MicroCAD) study. Presence of myocardial ischemia was detected by myocardial contrast stress echocardiography. Total plaque volume was determined as the difference between vessel and lumen volume in all coronary arteries using a semiautomatic CCTA quantification software.
Results: Patients with higher than median plaque volume (=1197 mm³) were older, had lower body mass index, higher calcium score and higher prevalence of myocardial ischemia (all p<0.05), while sex, prevalence of hypertension, diabetes or hypercholesterolemia did not differ. Total coronary artery plaque volume was higher in the 67 (52%) patients with ischemia (1264±308 mm³ vs. 1122±382 mm³, p=0.021) compared to non-ischemic patients. In univariate analysis, one standard deviation (SD) higher total coronary plaque volume was associated with presence of myocardial ischemia (OR 1.54 pr. mm³/SD [95% CI 1.06-2.23], p=0.024). The association remained significant even after adjusting for age, sex and calcium score (OR 1.51 pr. mm³/SD [95% CI 1.00-2.26], p=0.048).
Conclusion: In patients with stable angina and non-obstructive CAD, total coronary artery plaque volume was associated with presence of myocardial ischemia. Our results suggest that assessment of total coronary artery plaque volume may become a valuable diagnostic tool in non-obstructive CAD.