The present invention provides a method for prophylactically treating a vessel region at risk for the development of vulnerable plaque with cryogenic energy. In general, a cryogenic catheter is inserted into the patient's vascular network and manipulated towards a treatment site. The catheter is then activated so as to cool the tissue at the treatment site to a predetermined temperature for a desired amount of time in order to induce the formation of scar tissue, which may include collagen or smooth muscle cell formation. It is understood that a variety of cryogenic catheter configurations can be used to cool the treatment site.