Geometric vascular remodeling after balloon angioplasty and beta-radiationtherapy - A three-dimensional intravascular ultrasound study

Background-Endovascular radiation appears to inhibit intimal thickening aft er overstretching balloon injury in animal models. The effect of brachyther apy on vascular remodeling is unknown. The aim of the study was to determin e the evolution of coronary vessel dimensions after intracoronary irradiati on after successful balloon angioplasty in humans. Methods and Results-Twenty-one consecutive patients treated with balloon an gioplasty and beta-radiation according to the Beta Energy Restenosis Trial- 1.5 were included in the study. Volumetric assessment of the irradiated se gment and both edges was performed after brachytherapy and at 6-month follo w-up. Intravascular ultrasound images were acquired by means of EGG-trigger ed pullback, and 3-D reconstruction was performed by automated edge detecti on, allowing the calculation of lumen, plaque, and external elastic membran e (EEM) volumes. In the irradiated segments, mean EEM and plaque volumes in creased significantly (451+/-128 to 490.9+/-159 mm(3) and 201.2+/-59 to 241 .7+/-74 mm(3); P=0.01 and P=0.001, respectively), whereas luminal volume re mained unchanged (250.8+/-91 to 249.2+/-102 mm(3); P=NS). The edges demonst rated an increase in mean plaque volume (26.8+/-12 to 32.6+/-10 mm(3), P=0. 0001) and no net change in mean EEM volume (71.4+/-24 to 70.9+/-24 mm(3), P =NS), resulting in a decrease in mean luminal volume (44.6+/-16 to 38.3+/-1 6 mm(3), P=0.01). Conclusions-A different pattern of remodeling is observed in coronary segme nts treated with beta-radiation after successful balloon angioplasty. In th e irradiated segments, the adaptive increase of EEM volume appears to be th e major contributor to the luminal volume at follow-up. Conversely, both ed ges showed an increase in plaque volume without a net change in EEM volume.