Serum marker and CT characteristics of coronary calcified nodule assessed by intravascular ultrasound

BACKGROUND: Calcified nodule (CN) is a type of potentially vulnerable plaque. Its formation mechanism remains unknown. This study was to assess serum marker and computed tomography angiography (CTA) characteristics of CN validated by intravascular ultrasound (IVUS). METHODS: Patients who underwent coronary CTA followed by invasive coronary angiography and IVUS were retrospectively analyzed. Serum levels of alkaline phosphatase (ALP), gamma-glutamyltransferase, and calcium were collected. RESULTS: IVUS detected 128 de novo calcified lesions in 79 patients with coronary artery disease (CAD). CNs were identified in 11.4% (9/79) of patients and 9.4% (12/128) of lesions. Compared with patients with non-nodular calcified plaques, CN patients had higher serum level of ALP (82.00 vs 65.00 U/L, P = 0.022) and total plaque volume (673.00 vs 467.50 mm(3), P = 0.021). Multivariable analyses revealed that serum ALP level and total plaque volume were independently associated with the prevalence of CN in CAD patients with calcified plaques. At lesion level, the CN group had a higher frequency of moderate to heavy calcification on angiography (75.00% vs 40.52%, P = 0.017). In terms of CTA characteristics, plaques with CN had a more severe diameter stenosis (79.00% vs 63.00%, P = 0.007), higher plaque burden (85.40% vs 77.05%, P = 0.005), total plaque density (398.00 vs 283.50 HU, P = 0.008), but lower lipid percentage (14.65% vs 19.75%, P = 0.010) and fiber percentage (17.90% vs 25.65%, P = 0.011). Mean plaque burden is an independent predictor of the prevalence of CN in calcified plaques (odds ratio = 1.102, 95% confidence interval: 1.025–1.185, P = 0.009). The AUC is 0.753 (95% confidence interval: 0.615–0.890, P = 0.004). When using 84.85% as the best cutoff value, the diagnostic sensitivity and specificity of mean plaque burden for predicting the presence of CN within calcified plaques were 66.7% and 80.2%, respectively. CONCLUSIONS: CN had different CTA imaging features from non-nodular coronary calcification. The presence of a CN was associated with a higher serum ALP level and plaque burden.