Balloon angioplasty (PTCA) of left main (LM) stenoses is limited by frequent clinical restenosis. Directional coronary atherectomy (DCA) may be an effective alternative to PTCA due to its ability to achieve a greater postprocedural luminal diameter when treating bulky, eccentric plaques and aorto-ostial lesions. We analyzed the acute and long-term results following 24 DCA procedures in 22 patients with "protected" LM lesions. Acute success (residual stenosis < or = 40%, no major ischemic complications) was 88% overall, 100% in 13 planned procedures, and 73% in 11 adjunctive DCA procedures that followed suboptimal PTCA. Mean LM stenosis was reduced from 86% to 13% (P < 0.01). There were no procedural complications directly attributed to DCA. At a mean of 24 +/- 3 months, the clinical restenosis rate was 16%, survival was 100%, and event-free survival (freedom from death, MI, or repeat lesion-related interventions) was 89%. We conclude that DCA in protected LM lesions (1) can achieved excellent angiographic results with low procedural complication rates, (2) may succeed where PTCA yields suboptimal results, and (3) may provide late clinical outcomes superior to those of balloon angioplasty.