Coronary calcified lesions can exert serious effects on stent expansion. A calcium scoring system, based on optical coherence tomography (OCT), has been previously developed to identify relatively mild calcified lesions that would benefit from plaque modification procedures. Therefore, the present study aimed to establish a novel OCT-based scoring system to predict the stent expansion of moderate and severe calcified lesions. A total of 33 patients who underwent percutaneous coronary intervention (PCI; 34 calcified lesions were observed using coronary angiography) were retrospectively included in the present study. Coronary angiography and OCT images were subsequently reviewed and analyzed. Furthermore, a calcium scoring system was developed based on the results of multivariate analysis before the optimal threshold for the prediction of stent underexpansion in patients with moderate and severe calcified lesions was determined. The mean age of the patients was 67±10 years. The present analysis demonstrated that the final post-PCI median stent expansion was 70.74%, where stent underexpansion (defined as stent expansion <80%) was observed in 23 lesions. The mean maximum calcium arc, length and thickness, which were assessed using OCT, were found to be 230˚, 25.10 mm and 1.18 mm, respectively. A multivariate logistic regression model demonstrated that age and the maximum calcium arc were independent predictors of stent underexpansion. A novel calcium scoring system was thereafter established using the following formula: (0.16 x age) + (0.03 x maximum calcium arc) according to the β-coefficients in the multivariate analysis, with the optimal cut-off value for the prediction of stent underexpansion being 16.87. Receiver operating characteristic curve analysis demonstrated that this novel scoring system yielded a larger area under the curve value compared with that from a previous study's scoring system. Therefore, in conclusion, since the calcium scoring system of the present study based on age and the maximum calcium arc obtained from OCT was specifically developed in the subjects with moderate and severe calcified lesions, it may be more accurate in predicting the risk of stent underexpansion in these patients.

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.