Maximum calcium thickness is a useful predictor for acceptable stent expansion in moderate calcified lesions

Contemporary debulking devices such as rotational or orbital atherectomy can modify severe calcified lesions before stent implantation. Actually, we occasionally experience stent underexpansion without debulking devices in not severe but moderate calcified lesions although we expect good stent expansion. We aimed to investigate useful calcium parameters correlated with stent expansion in moderate calcified lesions. We enrolled 50 consecutive moderate calcified lesions in 47 patients who underwent optical coherence tomography (OCT) guided percutaneous coronary intervention (PCI) between January 2017 and March 2019. The exclusion criteria were the lesions without any calcium and treated with rotational or orbital atherectomy. We compared stent sizing, length, post balloon sizing, post balloon pressure, mean reference area, pre-procedure area stenosis and various calcium parameters including calcium arc, maximum calcium thickness, depth, longitudinal length in pre-PCI OCT with post-PCI stent expansion by simple and multiple regression analysis. Maximum calcium thickness was an independent predictor for stent expansion, while the other calcium parameters were not associated. The optimal thresholds of maximum calcium thickness for predicting acceptable stent expansion defined by 80% was 880 µm (area under curve: 0.73). Maximum calcium thickness < 880 µm is a useful predictor for acceptable stent expansion in moderate calcified lesions.