To assess the value of coronary angioplasty in calcified lesions we have prospectively compared the clinical, procedural and anatomic characteristics of 55 calcified lesions (group A) with 830 lesions without calcium (group B). Patients in group A were older (67.2 +/- 8 vs 58.8 +/- 11 years), had a higher incidence of 3 vessel disease (20% vs 8%, p less than 0.05), and received less frequently a complete revascularization (50% vs 68%, p less than 0.05). Lesions in group A were more frequently located in the left anterior descending coronary artery and tended to be longer (0.86 +/- 0.5 vs 0.67 +/- 0.5 cm, p less than 0.1) whereas were rare at distal segments (9% vs 19%, p less than 0.05). In addition, group A lesions were more eccentric (81% vs 58%, p less than 0.05), more irregular (67% vs 33%, p less than 0.05), and frequently were located at bifurcation (42% vs 26%, p less than 0.05). More balloon inflations were required in group A (4.1 +/- 2.4 vs 3.1 +/- 1.4, p less than 0.05), but the maximal pressures utilized were similar in both groups (7.9 +/- 2.5 vs 7.6 +/- 1.9 atm). Dilatation success was achieved in 80% of the lesions in group A vs 90.1% in group B (p less than 0.05). Univariate analysis revealed a trend towards a higher restenosis rate--per lesion--in group A (42.8% vs 30.5%, p less than 0.1), which was not longer present after step-wise logistic regression analysis.(ABSTRACT TRUNCATED AT 250 WORDS)