METHODS AND RESULTS - Three hundred and twenty three native coronary artery lesions in 303 patients (197 men, mean age 63.9 +/- 11.5 years) treated with Palmaz-Schatz stents were differentiated into four groups depending on their degree of circumferential calcification as defined by intravascular ultrasound [0-90 degrees (n=120), 91-180 degrees (n=58, 181-270$ (n=71) and 271-360 degrees n=74)]. In 117 lesions rotational atherectomy was used prior to stent placement. Intravascular ultrasound and quantitative angiography were performed prior to treatment and after stent placement to measure minimal and maximal lumen diameter and lumen cross-sectional area at the lesion site and the reference segments. Acute lumen gain and eccentricity index were calculated. Although higher balloon pressures were used than in the minimally calcified lesions. the final angiographic minimal lumen diameter decreased with increasing arc of calcification (3.01 +/- 0.47, 3.04 +/- 0.43, 2.85 +/- 0.53, 2.83 +/- 0.40 mm, respectively, P=0.0320) resulting in a decrease in acute diameter gain with increasing arc of calcification (2.06 +/- 0.51, 1.91 +/- 0.46, 1.81 +/- 0.56, 1.78 +/- 0.51 mm, respectively, P=0.0067). Adjunctive rotational atherectomy prior to stent placement resulted in a greater acute diameter and a greater lumen cross-sectional area gain, coupled with less final residual stenosis than pre-treatment with balloon angioplasty.

CONCLUSION - Implantation of stents in calcified lesions results in less optimal stent expansion, especially in lesions with thick, eccentric calcific plaque layers. Use of adjunctive rotational atherectomy before stent placement may improve the procedural result.