Background: The aim of this study was to investigate the angiographic and intravascular ultrasound (IVUS) changes following cutting balloon (CB) and percutaneous transluminal coronary angioplasty (PTCA) treatment in in-stent restenosis.
Methods: Fifty consecutive patients with in-stent restenosis were randomized to treatment with CB (n = 25) or PTCA (n = 25). The size of the device was selected using IVUS according to a 1:1 device-to-stent ratio and balloons were inflated to a maximal pressure of 8 atm. Quantitative coronary angiography (QCA) and IVUS (both planar and volumetric) evaluations were carried out before and after treatment and 24 hours later. In case of suboptimal results at 24 hours (> or = 50% diameter stenosis at QCA and/or < or = 4.7 mm2 minimal lumen area [MLA] at IVUS), the patients were re-randomized to receive additional treatment (CB for PTCA and vice versa) or to follow-up. Measurements included the minimal lumen diameter and diameter stenosis for QCA and the external elastic membrane area (EEMA), stent area (SA), MLA, restenosis area (RA = SA - MLA) and plaque + media area (PMA = EEMA - SA) for IVUS.
Results: A similar minimal lumen diameter increase (1.19 +/- 0.44 vs 1.37 +/- 0.55 mm) and diameter stenosis decrease (-37 +/- 14 vs -45 +/- 13%) was found after PTCA and CB. No significant difference was found in MLA increase (4.81 +/- 1.9 vs 5.45 +/- 2.0 mm2) and RA decrease (-3.8 +/- 1.3 vs -4.2 +/- 1.7 mm2) in PTCA and CB. SA, EEMA and PMA did not significantly change after treatment in either group. Of the total mean lumen enlargement after PTCA and CB, 20% was due to additional stent expansion and 80% was due to RA decrease. At 24 hours, a greater minimal lumen diameter increase (-0.23 +/- 0.34 vs -0.06 +/- 0.23 mm, p = 0.03) and MLA loss (-1.9 +/- 1.4 vs 0.37 +/- 0.8 mm2, p = 0.000) and RA increase (1.74 +/- 1.3 vs 0.37 +/- 0.52 mm2, p = 0.000) were detected in PTCA vs CB. Volumetric changes paralleled planar IVUS variations. A suboptimal result was more frequently found in PTCA as compared to CB (36 vs 4%, p < 0.01). At follow-up, PTCA had a higher target lesion revascularization as compared to CB (40 vs 12.5%, p < 0.05).
Conclusions: In in-stent restenosis, PTCA and CB share similar effects and mechanisms of lumen enlargement. In-stent tissue is mainly redistributed along a larger stent rather than being extruded out of the stent struts. At 24 hours, a significant lumen loss (instant restenosis) occurred more frequently in PTCA as compared to CB and may account for a higher target lesion revascularization in this group.