Effects of probucol on vascular remodeling after coronary angioplasty. Multivitamins and Protocol Study Group.

BACKGROUND We have shown that probucol reduces restenosis after balloon angioplasty. Whether probucol acted via prevention of neointimal formation or improvement in vascular remodeling could not be addressed by angiography and required the use of intravascular ultrasound (IVUS). METHODS AND RESULTS Beginning 30 days before angioplasty, 317 patients were randomly assigned to receive probucol, multivitamins, combined treatment, or placebo. Patients were then treated for 6 months after angioplasty. IVUS examination was performed immediately after angioplasty and at follow-up in 94 patients (111 segments). The cross section selected for serial analysis was the one at the angioplasty site with the smallest lumen area at follow-up. In the placebo group, lumen area decreased by -1. 21+/-1.88 mm2 at follow-up, and wall area and external elastic membrane (EEM) area increased by 1.50+/-2.50 and 0.29+/-2.93 mm2, respectively. Change in lumen area, however, correlated more strongly with the change in EEM area (r=0.53, P=0.002) than with the change in wall area (r=-0.13, P=0.49). Lumen loss was -1.21+/-1.88 mm2 for placebo, -0.83+/-1.22 mm2 for vitamins, -0.25+/-1.17 mm2 for combined treatment, and -0.15+/-1.70 mm2 for probucol alone (P=0.002 for probucol, P=0.84 for vitamins). Change in wall area was similar for all groups. EEM area increased by 0.29+/-2.93 mm2 for placebo, 0. 09+/-2.33 mm2 for vitamins only, 1.17+/-1.61 mm2 for combined treatment, and 1.74+/-1.80 mm2 for probucol only (P=0.005 for probucol). CONCLUSIONS Lumen loss after balloon angioplasty is due to inadequate vessel remodeling in response to neointimal formation. Probucol exerts its antirestenotic effects by improving vascular remodeling after angioplasty.