RESUMO
Endothelial dysfunction and inflammation play a crucial role in all stages of atherosclerosis, from the beginning, during progression, and, finally, in its highest clinical expression: acute coronary syndromes. In this process, fibrinogen, an acute phase reactant with active participation in endothelial function, thrombosis and inflammation has proved to be an independent variable to cardiovascular risk together with its participation in resistance phenomena to different antithrombotic approaches. The reasons by which fibrinogen is elevated in cardiovascular disease and atherosclerosis are, in general, only incompletely understood; but all cells involved in the atherogenetic process are able to produce cytokines, which induce an acute phase reaction that increases fibrinogen levels in plasma. The potential pathophysiological mechanisms by which elevated fibrinogen levels mediate cardiovascular risk are multiple. Fibrinogen forms the substrate for thrombin an represents the final step in the coagulation cascade, it is essential for platelet aggregation, it modulates endothelial function, it promotes smooth muscle cell proliferation and migration, it interacts with the binding of plasmin with its receptor and, finally, it represents a major acute phase protein. Epidemiological studies have established sufficient evidence to consider fibrinogen as a strong, consistent, and independent cardiovascular risk marker or factor. Based on all these implications, the target of this review is an analysis of physiopathogenic and epidemiologic evidence searching for guidelines to establish whether fibrinogen as a risk factor or marker is the lost link between cardiovascular disease and classic risk factors. CONCLUSION: Analyses of the respective studies suggest that fibrinogen is an important and independent cardiovascular risk factor, clearly associated with conventional risk factors and genetic polymorphisms. Whether or not fibrinogen is causally involved in atherothrombogenesis still remains to be determined and despite of unsolved issues that are waiting conclusive answers, fibrinogen has emerged as an important additional marker of cardiovascular risk.