3 Myths About New Oral Anticoagulants Debunked for Primary Care Physicians

One of the major advantages to, and a primary reason for adoption of, the novel oral anticoagulants (NOACs) is the fact the they don’t require strict biochemical monitoring the way that vitamin K antagonists do. For this reason, however, many patients and physicians believe that no monitoring is needed at all. Although it is true that no monitoring is needed to verify the efficacy of anticoagulation with NOACs (as with INR monitoring with warfarin), liver/renal function, hemoglobin level, and medication compliance all need to be evaluated regularly.

Dabigatran adherence was only 76.8% for the first year after diagnosis of AF in a nationwide Danish study of 2960 patients.(1,2) Adherence ranged from 42% to 93%; clinical factors associated with poor adherence included medical comorbidities and low socioeconomic status.(2) Although no monitoring of degree of anticoagulation is needed, if a dose is missed, there is a risk of a gap in anticoagulation. Proper patient selection and education are essential as is routine assessment of patient compliance. The European Society of Cardiology (ESC) recommends annual Hb, liver, renal function monitoring (more often if reduced CrCl) while taking NOACs in case there are adverse reactions or dose adjustment is needed.

The NOACs have penetrated many therapeutic arenas, including anticoagulation for AF, deep vein thrombosis (DVT), and pulmonary embolism (PE). However, as we gain familiarity with these agents, novel applications continue to be uncovered; a key example is the use of NOACs in the pericardioversion period-an important application for which data are now emerging.

Study: Cleveland Clinic collected data (2009-2013) on 4647 patients undergoing DCCV with adequate follow-up: Patients were taking: warfarin (80%); dabigatran (15.5)%; rivaroxaban (3.4%); apixaban (1%).(1) No differences found in rates of CVA/TIA (P=.16) or bleeding (P=.25); both very low overall. Overall NOAC utilization in patients with AF has increased. NOACs appear to have a similar efficacy and safety profile to warfarin with respect to DCCV and offer a more convenient alternative. Specifically, they obviate the need for periprocedural INR monitoring if compliance is assured. Furthermore, a patient who is taking an NOAC does not necessarily need to be transitioned to warfarin or heparin prior to cardioversion.

Anticoagulation prior to AF ablation, which requires a trans-septal puncture and “left-sided” (arterial sided) pulmonary vein ablation has been a mainstay of therapy to avoid systemic thromboembolism. However, until recently, there have been limited data on the safety and efficacy of NOACs prior to this procedure.

Adoption of periprocedural NOAC use has been slow, but data suggest no increase in rates of bleeding complications when given prior to AF ablation. Study: 301 patients undergoing AF ablation for paroxysmal (71%) or persistent (29%) AF divided into 3 groups: Uninterrupted warfarin with therapeutic INR (WARF) n=114; Dabigatran (n=89) until 24 hours before procedure-heparin 6 hours post-procedure; Rivaroxaban (n=98) until 36 hours before-heparin 6 hours post-procedure.

No difference in thromboembolic/bleeding risk among the groups. WARF vs dabigatran vs rivaroxaban, 6.2% vs 6.7% vs 6.0%, P=.82. CAVEAT: Like this study, sample sizes in others are also small and results need validation in larger cohort