BACKGROUND: Rotational atherectomy(RA) uses a high speed, rotating, diamond-tipped elliptic burr to abrade atherosclerotic plaque to increase lumen size. Differential forward cutting with RA burr results in ablation of diseased plaque, leaving the nomal, uninvolved arterial wall intact. Increased lesion length, increased lesion angulation and lesion calcification were predictive of an abrupt closure after balloon coronary angioplasty(balloon PTCA). RA facilitates the treatment of distal, tortuous and difficult-to-cross lesion. We evaluated the usefulness of RA as initial treatment modality in type B2 or C lesions, comparing with the balloon PTCA. METHOD: RA with adjunctive balloon PTCA were performed in 94 patients with 101 lesion sites(M/F:68/26, age:59.5+/-10.0 years) and balloon PTCA were performed in 245 patients with 293 lesion sites(M/F:188/57, age:58.7+/-10.3 years). Lesion analysis using a modified American College of Cardiology/American Heart Association classification system(ACC/AHA) showed that type B2 lesion was 35.6% and 64.5%, type C lesion was 64.4% and 35.5% in RA/adjunctive balloon PTCA and balloon PTCA, respectively. RESULTS: According to modified ACC/AHA lesion classification, type C lesion was higher percentage(64.4% vs 35.6%) in RA with adjunctive balloon PTCA compared with balloon PTCA and B2 lesion was higher percentage(64.5% vs 35.6%) in balloon PTCA(p<0.05). Diffuse lesion(61.4% vs 23.9%), irregular lesion(81.2% vs 65.5%), and heavily calcified lesion(40.6% vs 8.9%) were more commonly noted adverse morphologic features in RA with adjunctive balloon PTCA compared with balloon PTCA(p<0.05). However, total occlusion(25.9% vs 16.9%) was more common in balloon PTCA(p<0.05). Procedural success was achieved in 84.1% of RA with balloon adjunctive PTCA and in 82.3% of balloon PTCA. Myocardial infarction occurred in 2 patients(2.1%) and 4 patients(1.6%) in RA with adjunctive balloon PTCA and balloon PTCA, respectively. There were no procedural deaths or emergency surgeries in both groups. One case of cardiogenic shokc, 3 cases of no-reflow and 3 cases of wire embolization occurred in RA with adjunctive balloon PTCA. CONCLUSION: The overall success rate of RA appears to be similar to that of balloon PTCA despite of more complex lesion morphology(long lesion segment, irregularity and heavy calcification). RA is safe method of initial treatment modality with a high success rate in type B2 or C lesion. Longterm result after RA remains to be determined.