What is the remaining use of vitamin K antagonists in the elderly?

Abstract

With the recent marketing of the new oral anticoagulants (NOAC), the future of vitamin k antagonist (VKA) needs to be redefined. VKAs are drugs with a narrow therapeutic margin and a high iatrogenic risk that requires a close biological monitoring. Their efficacy has been proven for atrial fibrillation in numerous populations, especially in the elderly. Their side effects and interactions are well known. The measurement of the level of anticoagulation is possible and reliable using the INR (international normalized ratio) and an antidote is usable in case of emergency. The NOAC are at least as effective as VKA with slightly less side-effects especially cerebral hemorrhage, and they do not require biological monitoring. However, data on efficacy and side-effects of NOAC rely mainly on phase III clinical trials that did not particularly target polypathologic and frail populations. In these populations, we therefore have more "real life" information on VKA than NOAC. But studies on NOAC are currently conducted among these populations. A conservative approach would be to maintain VKA to older patients with stable INR. Lastly VKA are the only anticoagulant usable in case of severe renal failure and valvular fibrillation.