A Novel Optical Coherence Tomography-Based Calcium Scoring System Can Predict Stent Expansion of Moderate and Severe Calcified Lesions

Abstract

Background: Coronary calcified lesions have a serious effect on stent expansion. Researchers have developed a calcium scoring system based on optical coherence tomography (OCT) to identify relatively mild calcified lesions that would benefit from plaque modification. The present study is designed to establish a novel OCT-based scoring system to predict stent expansion of moderate and severe calcified lesions.Methods: The present study retrospectively included 33 patients (34 calcified lesions observed on coronary angiography) who underwent OCT-guided percutaneous coronary intervention (PCI) at Peking University People's Hospital from January 2016 to July 2021. We off-line reviewed and analysed the images of coronary angiography and OCT. We then developed a calcium scoring system and found the optimal threshold for the prediction of stent underexpansion in patients with moderate and severe calcified lesions.Results: The average age of the patients was 67 years. Overall final post-PCI stent expansion was 70.74%, and poor stent expansion (i.e., stent expansion < 80%) was seen in 23 lesions. Approximately 89% of the lesions manifested as angiographically visible moderate and severe coronary calcification. The average maximum calcium arc, length and thickness assessed by OCT were 230°, 25.10 mm and 1.18 mm, respectively. Multivariate logistic regression model showed that age (OR: 1.173, 95% CI: 1.036~1.438, p = 0.042) and maximum calcium arc (OR: 1.023, 95% CI: 1.008~1.050, p = 0.021) were independent predictors of stent underexpansion. A novel calcium scoring system was established as: 0.16 × age + 0.03 × maximum calcium arc, and the best cut-off of the system for the prediction of stent underexpansion was 16.87 (sensitivity 0.870, specificity 0.909, area under the curve [AUC] 0.925, 95% CI: 0.836~1.014, p < 0.001). Receiver operating characteristics curve analysis showed that the novel scoring system had larger AUC than the previous scoring system (0.925 vs 0.706, p = 0.002).Conclusions: The calcium scoring system based on age and maximum calcium arc obtained from OCT may more accurately predict the risk of poor stent expansion in patients with moderate and severe calcified lesions.