Although significant coronary artery (CA) calcification is believed to affect stent deployment, the exact impact on stent deployment after high-pressure balloon inflations is unknown. Intracoronary intravascular examination (ICUS) was performed in 27 moderate-severe calcified CA lesions before and after stent implantation. In case of unsatisfactory results (in-stent area < 90%, minimal in-stent diameter/maximal in-stent diameter < 0.8), further inflations up to 20 atm guided by ICUS were applied. Initially, stent expansion was adequate in 10 stents (37%) and symmetric in 19 (70%). After inflation at 20 atm, stents with adequate expansion increased to 16 (59%, P = 0.0036), but stents with symmetry decreased to 13 (48%, P = 0.0045). Stent expansion was inversely correlated to the arc of calcium (r = -0.8, P < 0.0001). There were five patients with clinical restenosis at 6 months (18%). Increases in stent lumen area with high-pressure balloon inflations in moderate-severe calcified CA lesions are at the expense of symmetry. This may affect clinical restenosis.