Serial photon-counting coronary computed tomography angiography for surveillance of plaque progression in patients with symptomatic coronary artery disease

Background Despite guideline-directed therapies, patients with coronary artery disease (CAD) experience recurrent events from residual plaque progression. Photon-counting coronary computed tomography angiography (CCTA) is an advanced technology for imaging whole-heart atherosclerosis non-invasively. Purpose To use serial photon-counting CCTA to 1) measure quantitative changes in residual coronary atheroma over a 12-month period in patients with symptomatic CAD, 2) define which clinical and biochemical factors associate with plaque progression, and 3) assess differences between groups of atheroma progression status. Methods This prospective multicentre study recruited patients with residual CAD after clinically indicated invasive coronary angiography and intervention. Participants underwent standardised photon-counting CCTA (sequential mode, 120 kVp) within 30 days and 12 months later. Local core-laboratory, quantitative plaque analysis was performed using adaptive-threshold, artificial intelligence-enabled software (Autoplaque v3.0) to quantify plaque changes in unstented coronary segments with plaque. Plaque progression was defined as a ≥2% increase and regression as a ≥2% decrease in total plaque burden over one-year. Results 100 of 117 participants completed both CCTA visits, with median age 62 years, 76% were male, with 85% recent ACS, and 95% on statins at follow-up. Quantitative plaque measurements demonstrated excellent reliability with an intra-class correlation coefficient of 0.948 (95% CI: 0.874, 0.979) and a median intra-observer variation of 1.1% (IQR -0.6, 1.8) for total plaque burden. Total plaque burden increased by 1.0% (95% CI 0.0, 1.9; P=0.049) over one-year. Calcified plaque burden increased by 1.3% (95% CI 1.0, 1.5; P<0.001), but non-calcified plaque burden did not change significantly (-0.3%; 95% CI -1.2, 0.6; P=0.507). 39% of participants had progression of total plaque, 29% regression and 32% stable disease (Figure 1A), with a similar pattern for non-calcified plaque (Figure 1B) and low-density non-calcified plaque (Figure 1C), while calcified plaque increased (Figure 1D). Factors associated with total plaque burden progression on linear regression (Figure 2) were younger age, male sex, poorer renal function and lower baseline total plaque burden, with no associations with baseline LDL-C. Despite quantified variation in plaque changes (Figure 3), there were no differences between progressor and regressor groups for traditional risk factors or high-intensity statin use. Conclusions With clinician-directed care, almost 40% of patients experienced residual atheroma progression one-year after clinically indicated invasive coronary angiography, highlighting scope for more intensive treatment, and a role for serial CCTA to monitor plaque changes and tailor anti-atherosclerotic therapies in patients with established CAD.