Substantial impact of temporary interruptions of warfarin versus DOAC

Results from the ORBIT-AF registry have shown that the International Normalised Ratio (INR) is not therapeutic following temporary interruption of warfarin in roughly 50% of the patients at 2 weeks. Interruption of warfarin is also associated with low time in therapeutic range (TTR) for more than 6 months after the interruption. Additionally, temporary interruption of warfarin is associated with a higher incidence of adverse cardiovascular events when compared with a direct oral anticoagulant (DOAC) [1].

It might be necessary for patients with atrial fibrillation (AF) to temporarily interrupt their oral anticoagulation, for example when undergoing a surgical procedure. In the case of warfarin, this may result in an INR that is subtherapeutic for some days after re-initiation, which may lead to an increase in thromboembolic events. For DOAC this is different as patients on these drugs attain therapeutic OAC as soon as the drug is restarted, which may result in a lower risk of adverse events.

The study, presented by Dr Malini Madhavan (Mayo Clinic, USA), aimed to describe the basic characteristics of patients with temporary interruption and characteristics of temporary interruptions, to study TTR before and after a temporary interruption of warfarin, and to compare the outcome events after temporary interruption of warfarin vs DOAC. They used data from 9,749 patients aged 18 and over with electrocardiogram (ECG) evidence of AF enrolled in the multicentre ORBIT-AF registry. Temporary interruption of oral anticoagulant was defined as interruption for a procedure followed by re-initiation of the same drug. At least 1 temporary interruption occurred in 2,166 patients on warfarin and 269 patients on DOAC (of which rivaroxaban n=26 and dabigatran n=243).

Patients on warfarin had a total of 3,022 interruptions. The TTR was significantly lower than before temporary interruption of warfarin. At 3 months, the percentage time of sub-therapeutic INR was 15.9% (prior to temporary interruption) vs 17.3% after temporary interruption (P<0.0001). At 6 months, this was 15.9% vs 18.2%, respectively (P<0.0001). Patients who used a DOAC had a total of 329 interruptions with 52 patients having >1 interruption. Patients who used warfarin had a higher incidence of the composite endpoint of cardiovascular death, stroke/transient ischaemic attack, myocardial infarction, or major bleeding when compared with patients using a DOAC (see Table).

Table: Outcomes after temporary interruption of warfarin vs DOAC [1]



CV, cardiovascular; CNS, central nervous system; DOAC, direct oral anticoagulant; MI, myocardial infraction; TIA, transient ischaemic attack.

1. Madhavan M, et al. Abstract 1267-267. ACC 2019, 16-18 March, New Orleans, USA.



Posted on 4 June 201917 March 2021