Objective Accelerated left main coronary stenosis (LMCS) is a known potential late complication of coronary artery catheter procedures. The aim of this study was to assess the current occurrence of LMCS as a delayed complication of percutaneous angioplasty (PTCA) of the left coronary branches in our institution. Methods The medical records of patients referred for coronary artery by-pass surgery from the same Cardiology Unit in the January 2003 to December 2006 period and presenting a significant (> 50%) LMCS as a new finding following a PTCA of the left coronary artery branches, were reviewed. Patients with retrospective evidence of any LMCS at previous coronary angiographies preceding the percutaneous procedure were excluded. Results Thirty-seven patients (5 females, mean age 71.1±8.6 years) out of 944 (4%) having undergone a PTCA, fulfilled the inclusion criteria, 19 (51%) after a procedure also involving the LAD coronary artery. Extraback-up guiding catheters were used in most cases. Use of multiple wires or balloons was observed in 3 cases (8%). Rotablator and proximal occlusion device were used in one case respectively (3%). Twenty patients (54%) have had more than one percutaneous coronary intervention on the left coronary branches. The mean time elapsed from the first angioplasty and surgical intervention was 18.1±7.8 months. Conclusions The potential occurrence of LMCS following a percutaneous intervention procedure, especially when complicated and repeated, should not be underestimated in the current era. This evidence may offer the rationale to schedule non-invasive imaging tests to monitor left main coronary patency after the procedure as well as to fuel further research to develop less traumatic materials.