An apparatus for interventional treatment of atherosclerosis at a vascular bifurcation includes structure for receiving a first guidewire and a second guidewire. An exit for the second guidewire is located in a central section of the structure. A first balloon portion is secured to the structure so a proximal end is located adjacent the exit. A second balloon portion is secured to the structure so a distal end is located adjacent the exit on a side of the exit opposite the first balloon portion. An annular gap is defined between the proximal end of the first balloon portion and the distal end of the second balloon portion. The annular gap, at a radial outermost location relative to the structure, has a width that is equal to or less than a width of the annular gap at a radially innermost location relative to the structure. The apparatus also includes an expandable stent that is mountable about the first and second balloon portions.