Conventional balloon angioplasty (PTCA) of ostial lesions (OL) is associated with suboptimal results and a higher complication rate. Partial plaque ablation with rotational atherectomy (RA) before PTCA might improve results. This approach was used in 63 patients (pts) (mean age 64+/-10 yrs; 44 men, 19 women) with 69 OL. There were 15 aorto-OL and 54 branch-OL. Calcification was more frequent in aorto-OL than in branch-OL (67% vs. 35%, P<0.05). Mean burr size was 1.8+/-0.3 mm. Burr-artery ratio was 0.74+/-0.10. Adjunctive PTCA was systematically performed. Procedural success was achieved in 58 pts (92%): 14 aorto-OL (93%) and 50 branch-OL (93%) were successfully treated; major complications occurred in 1 (7%) aorto-OL and 1 (2%) branch-OL. Uncomplicated failure occurred in three cases. Minimal lumen diameter (MLD) increased from 0.69+/-0.31 mm before RA to 1.43+/-0.28 mm after PA (P<0.001) and 2.16+/-0.29 mm after PTCA (P<0.001). Diameter stenosis (DS) decreased from 75+/-13% before RA to 32+/-12% after RA (P<0.001) and 14+/-10% after PTCA (P<0.001). All successfully treated pts underwent repeat angiography 24 h later and exercise testing or repeat cardiac catheterization >6 mo later. At 24 h repeat angiography, os was 17+/-15% (P=NS vs. after PTCA); no lesion had a DS greater than or equal to 50%. Follow-up coronary angiography was performed in 30 pts (52%) who had abnormal stress testing: 13 pts (43%) showed angiographic restenosis in at least one successfully treated OL. In conclusion, RA with adjunctive PTCA is a safe and effective treatment of OL. It is associated with higher success and lower major complications rates when compared with conventional PTCA. Restenosis remains a major limitation of all percutaneous approaches. (C) 1994 Wiley-Liss, Inc.