A device and method for intravascular treatment of atherosclerotic plaque prior to balloon angioplasty which microperforates the plaque with small sharp spikes acting as serrations for forming cleavage lines or planes in the plaque. The spikes may also be used to transport medication into the plaque. The plaque preparation treatment enables subsequent angioplasty to be performed at low balloon pressures of about 4 atmospheres or less, reduces dissections, and avoids injury to the arterial wall. The subsequent angioplasty may be performed with a drug-eluting balloon (DEB) or drug-coated balloon (DCB). The pre-angioplasty perforation procedure enables more drug to be absorbed during DEB or DCB angioplasty, and makes the need for a stent less likely. Alternatively, any local incidence of plaque dissection after balloon angioplasty may be treated by applying a thin, ring-shaped tack at the dissection site only, rather than applying a stent over the overall plaque site.