Catheter-based treatment of calcified coronary stenosis represents a major challenge. Complete revascularization often cannot be achieved in severely calcified lesions. Mortality after 3 years has been reported more than twice as high as in lesions without relevant calcification. Depending on the extent of the calcification, there is an increasing frequency of death, including cardiac death, myocardial infarction, and recurrent revascularizations. One of the reasons for the inferior results is incomplete stent deployment, even at higher balloon pressures. It has been shown that at inflation pressures of 20 atm, stent expansion correlates inversely with the degree of circular calcification. The clinical evidence from randomized trials for the interventional treatment of calcified lesions is limited. The recommendations in the guidelines are correspondingly cautious. The European Society of Cardiology guidelines on myocardial revascularisation of 2018, for example, refer to the significant importance of lesion preparation. Furthermore, depending on the extent of calcification, cutting and scoring balloons or rotational atherectomy (RA) are recommended in addition to conventional angioplasty. In cases of severe calcification, some authors recommend primarily using a debulking strategy in the form of orbital or rotational atherectomy.