['Restenosis of diffuse in-stent stenosis (> 10 mm) treated with percutaneous transluminal coronary angioplasty (PTCA) is as high as 80%. The excessive tissue-hyperplasia led to debulking before PTCA. Because debulking is limited by the intensity and applicability of its use, the large debulking trials were criticized and showed no major benefit. Considering that a significantly greater diameter than its own diameter can be ablated by the Eccentric Excimer Laser (eccELCA), we evaluated its effectiveness and safety in a prospective study.', 'Thirty-nine patients with diffuse in-stent restenosis (3.4 +/- 0.6 mm diameter; 14 +/- 9 mm in length) were treated by EccELCA followed by PTCA. In addition to clinical/angiographic target lesion revascularization (TLR) and major adverse cardiac events (MACE), the study endpoints were diameter stenosis (DS) and minimal lumen diameter (MLD), which were calculated before EccELCA, after EccELCA, after adjunctive PTCA and at 6-month follow-up.', 'Procedural success was 99.8%. Delivered laser energy was 2,134 +/- 856 Joules. DS decreased from 84 +/- 14% to 23 +/- 11% after eccELCA (p = 0.0018) to 9 +/- 5% after PTCA (p = 0.001) and was 31 +/- 12% at follow-up (p = 0.0041). MLD increased from 0.7 +/- 0.2 mm to 2.2 +/- 0.4 mm after EccELCA (p = 0.0017), to 2.7 +/- 0.4 mm after PTCA (p = 0.001) to 1.7 +/- 0.3 mm at follow-up (p = 0.0049). Maximal balloon inflation pressure was 9.4 +/- 4.0 atmospheres. At follow-up angiography, TLR = 23.1%, clinical TLR = 12.8%, and MACE = 0%.'] Does high-energy eccentric excimer laser angioplasty for debulking diffuse iIn-stent restenosis lead to better acute- and 6-month follow-up results?