Anticoagulant therapy in patients with
atrial fibrillation requires careful evaluation because its benefits i.e. prevention of
thromboembolism, must be greater than the risk of
bleeding. Patients at higher risk of
thrombosis are evaluated through specific scores, such as the CHA(2)DS(2)VASc, coupled with scoring systems for assessing
bleeding risks, such as the HAS-BLED score. In addition to
bleeding, other risks have been associated with the use of
warfarin, including an increased susceptibility to
vascular calcifications and fractures caused by a reduction in the levels of
vitamin K dependent carboxylated
enzymes,
matrix Gla-protein (MGP) and
bone Gla-protein or
osteocalcin (BGP). In fact, while on one side
warfarin is used to prevent
embolism, on the other hand acting as a
vitamin K antagonist it blocks the inhibitory effect of MGP on
vascular calcification. Similarly, patients treated with
warfarin carry a greater risk of developing
osteoporosis and fractures, due to reduced BGP activity. Recently, a new generation of
anticoagulant drugs has been developed, such as
dabigatran, a
direct thrombin inhibitor, and
rivaroxaban, a
direct factor-Xa inhibitor. They offer an interesting alternative to
warfarin, because they do not require frequent blood tests for monitoring while offering similar results in terms of efficacy. Lacking the inhibitory effect on the
vitamin K cycle, the consequent side effects can be avoided. If, compared to
warfarin treated patients, a lower incidence of
vascular calcifications and fractures will be demonstrated, the advantages over
warfarin may be even greater, leading to further benefits in terms of morbidity and mortality.