Oxidized LDL leads to the release of chemotactic factors from nearby cells; factors which signal leukocytes to migrate to the site. Recall that atherosclerosis is believed to be caused by phagocytic cells such as macrophages, which ingest LDL particles and turn into stationary foam cells. Macrophages have been shown to have increased affinity for oxidized LDL. Thus, oxidation makes LDL more susceptible to phagocytosis and therefore more atherogenic.
Since oxidized LDL is more atherogenic than native LDL it makes sense that oxidized LDL may be a cardiovascular risk marker. Indeed, many studies have now correlated increased levels of oxidized LDL with risk of cardiac events.