AbstractThe aim of the study was to evaluate the feasibility, safety, and efficacy of cutting balloon angioplasty in treatment of angiographically moderate and severe calcified coronary lesions. Thirty‐seven calcified coronary lesions (29 patients) detected by angiography were dilated with cutting balloon. Predilatation with plain balloon was performed in 27 (73.0%) lesions and stent was implanted in 23 (62.2%) lesions following cutting balloon. Acute gain following cutting balloon in predilated lesions was compared to the acute gain following plain balloon predilatation. For predilated lesions, acute gain after cutting balloon was significantly greater compared with plain balloon predilatation (1.51 ± 0.49 vs. 0.77 ± 0.42; P = 0.01). This result was achieved with larger size and lower pressure of cutting balloon compared with plain balloon (3.28 ± 0.46 vs. 2.94 ± 0.55, P = 0.01; 10.38 ± 1.64 vs. 13.19 ± 3.63, P = 0.001, respectively). The final gain following cutting balloon dilatation was significantly higher than the expected gain obtained by using a plain balloon of the same size (1.51 ± 0.49 vs. 0.93 ± 0.48; P < 0.0001), which was inflated at significantly higher pressure compared with cutting balloon. When we compared acute gain following cutting balloon in lesions with and without predilatation, we found no significant difference (P = 0.31). Angiographic success was achieved in 36 (97.3%) lesions and procedural success in 33 (89.1%) lesions. In‐hospital major adverse cardiac event (MACE) occurred in three (10.3%) patients. Follow‐up MACE was reported from three (10.3%) patients. In conclusion, cutting balloon angioplasty is feasible and safe in treatment of angiographically moderate and severe calcified lesions. Dilating efficiency of cutting balloon seems to be greater compared with a plain balloon of the same size, which was inflated at significantly higher pressure compared with cutting balloon. These results can be achieved with low in‐hospital MACE and are associated with a good long‐term outcome. Cathet Cardiovasc Intervent 2001;54:473–481. © 2001 Wiley‐Liss, Inc.