The high-risk criteria low-attenuation plaque <60 HU and the napkin-ring sign are the most powerful predictors of MACE: a long-term follow-up study

To assess the prognostic value of coronary CT angiography (CTA) for prediction of major adverse cardiac events (MACE) over a long-term follow-up period.

A total of 1469 low-to-intermediate-risk patients (65.9 years; 44.2% females) were included in our prospective cohort study. CTA was evaluated for (i) stenosis severity (minimal <10%; mild <50%; moderate 50–70%; severe >70%), (ii) plaque types (calcified, mixed dominantly calcified, mixed dominantly non-calcified, non-calcified), and (iii) high-risk plaque criteria [low-attenuation plaque (LAP) quantified by HU, napkin-ring (NR) sign, spotty calcification <3 mm, and remodelling index (RI)]. Over a follow-up of mean 7.8 years, MACE rate was 41 (2.8%) and 0% in patients with negative CTA. MACE rate increased along with stenosis severity by CTA (from 1.3 to 7.8%) (P < 0.001) and was higher in T3/T4 plaques than in T2/T1 (7.8 vs. 1.9%; P < 0.0001). LAP density was lower (35.2 HU ± 32 vs. 108.8 HU ± 53) (P < 0.001) and both NR-sign prevalence with n = 26 (63.4%) vs. n = 40 (28%) and LAP <30, <60, and <90 HU prevalence with 46.3–78% vs. 2.4–7% were higher in the MACE group (P < 0.001). On univariate and unadjusted multivariable proportional Hazards model, LAP <60 HU and NR were the strongest MACE predictors (HR 4.96; 95% CI: 2.0–12.2 and HR 3.85; 95% CI: 1.7–8.6) (P < 0.0001), while spotty calcification (HR 2.2; 95% CI: 1.1–4.3, P < 0.001), stenosis severity, and plaque type (HR 1.5; 95% CI: 1.1–2.3 and HR 1.7; 95% CI: 1.1–2.6) (P < 0.001) were less powerful. After adjusting for risk factors, CTA stenosis severity, and plaque type, LAP <60 HU and the NR sign remained significant (P < 0.001), while the effect of NR sign was even enhancing. HRP criteria were independent predictors from other risk factors.

Prognosis is excellent over a long-term period if CTA is negative and worsening with an increasing non-calcifying plaque component. LAP <60 HU and NR sign are the most powerful MACE predictors.