Background and aims: Previous studies have shown positive effects of intensive low-density lipoprotein (LDL) lowering therapy on atheroma volume using invasive intravascular ultrasound. Our study describes the changes in coronary plaque composition on coronary CT angiography (cCTA) in patients treated with proprotein convertase subtilisin kexin type 9 (PCSK9) inhibitors.

Methods: In this prospective study coronary plaques were analyzed using third generation dual-source CT before and after one year of PCSK9-inhibitor treatment. Plaque markers included total plaque volume (TPV), calcified (CPV), non-calcified (NCPV), fibrotic and lipid-rich plaque volume, lumen (LV) and vessel volume (VV), aggregate plaque volume (APV), minimal luminal area (MLA), minimal lumen diameter (MLD), lesion length (LL), corrected coronary opacification (CCO), and eccentricity and remodeling index (RI). Primary endpoint was defined as change in TPV, secondary endpoint was TPV or CPV regression or nominal change in plaque parameters.

Results: We analyzed 74 coronary plaques in 23 patients (60 ±9 years, 65% male). After one year of PCSK9-inhibitor treatment, LDL was reduced from 148 to 66 mg/dL (p<0.0001). Significant changes were found for VV (196 to 215 mm³, p=0.0340), MLA (3.1 to 2.6 mm², p=0.0413) and MLD (1.7 to 1.4 mm, p=0.0048). TPV, CPV, NCPV, fibrotic and lipid rich plaque volume, LV, APV, LL, eccentricity and RI did not change significantly (p>0.05).

Conclusions: Coronary artery plaque analysis by cCTA highlights that LDL-lowering therapy affects plaque composition. Our primary endpoint of TPV change was not reached, however VV, MLA and MLD changed significantly.