High-definition intravascular ultrasound versus optical frequency domain imaging for the detection of calcium modification and fracture in heavily calcified coronary lesion

Evaluation of the thickness of coronary calcium by 60-MHz intravascular ultrasound: head-to-head comparison with optical frequency domain imaging

The region behind the coronary calcium could not be visualized by intravascular ultrasound (IVUS) because of acoustic shadow. However, some pathological studies have shown that IVUS delineated the vessel border behind thin coronary calcium sheets. This study aimed to reveal whether recent IVUS can visualize the region behind thin coronary calcium sheets. Using 534 cross-sectional optical frequency domain images (OFDI), including severe calcified coronary lesions, calcium sheet thickness was measured by every 1°. Accordingly, the visibility of the vessel border behind the coronary calcium sheet was evaluated using 60-MHz IVUS images, which were longitudinally linked with OFDI ones. After carefully coordinating with the axial position, the association between the IVUS-derived permeability of the coronary calcium sheet and calcium thickness was evaluated. The maximum and mean calcium thickness by OFDI was 0.88 ± 0.39 and 0.62 ± 0.30 mm, respectively. By 60-MHz IVUS, 12.1% of the coronary calcium sheets had permeable segments. Comparing between OFDI and IVUS images, 48.6% of the coronary calcium sheets with maximum thickness ≤ 0.3 mm were sometimes permeable by 60-MHz IVUS, whereas most > 0.5 mm thick calcium sheets were impermeable. In the receiver operating characteristic curve analysis, the best cutoff values for the maximum and mean thickness of permeable calcium were 0.48 and 0.31 mm, respectively. Thus, 60-MHz IVUS can occasionally visualize the region behind a thin coronary calcium sheet. When using 60-MHz IVUS, this finding may be a predictive marker of calcium sheet with a thickness of < 0.5 mm.

Impact of ultrasound reverberation in calcified coronary arteries: Intravascular ultrasound study

BACKGROUND AND AIMS

Intravascular ultrasound (IVUS) often allows us to observe reverberations behind calcification in percutaneous coronary intervention (PCI) to heavily calcified lesions. However, clinical significance of reverberations remains unknown. The aim of this study was to assess the impact of reverberations on stent expansion and clinical outcomes after PCI with rotational atherectomy (RA) to heavily calcified lesions.

METHODS

We considered 250 calcified lesions that underwent IVUS-guided PCI with RA. According to the number of reverberations (NR), those lesions were divided into the high NR (≥3) group (n = 36) and the low NR (≤2) group (n = 214). Stent expansion and the cumulative incidence of ischemia-driven target lesion revascularization (ID-TLR) were compared between the high and low NR groups.

RESULTS

The high NR group showed significantly smaller stent expansion rate than the low NR group (67.7% vs. 75.9%, respectively, p=0.02). The multivariate logistic regression analysis showed that high NR and calcified nodule were significantly associated with stent underexpansion. The incidence of ID-TLR was significantly higher in the high NR group than in the low NR group (p=0.03). In multivariate Cox hazard analysis, high NR and acute coronary syndrome were significantly associated with ID-TLR.

CONCLUSIONS

High NR was significantly associated with stent underexpansion and ID-TLR. When high NR was detected by IVUS, the PCI strategy was be planned carefully to avoid stent underexpansion. The follow-up program of the patients with high NR might need to be scheduled prudently because of the high risk of TLR.