Highlights from

ACC 2019

American College of Cardiology Annual Scientific Session & Expo

New Orleans 16-18 March 2019

Substantial impact of temporary interruptions of warfarin versus DOAC

Following temporary interruption of warfarin, the International Normalized Ratio (INR) is not therapeutic in roughly 50% of the patients at 2 weeks. It 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 (CV) events when compared with a direct oral anticoagulant (DOAC).

It might be necessary for patients with atrial fibrillation (AF) to temporarily interrupt their oral anticoagulation (OAC), 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 by Madhavan et al. 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 [1]. They used data from 9,749 patients aged 18 and over with ECG evidence of AF enrolled in the ORBIT-AF registry. Temporary interruption of OAC 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 subtherapeutic 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 CV death, stroke/transient ischaemic attack, myocardial infraction, or major bleeding when compared with patients who used DOAC.

Madhavan M, et al. The Impact of Temporary Interruptions of Warfarin on Downstream Time in Therapeutic Range in Patients With Atrial Fibrillation: Results From ORBIT AF. Abstract 1267-267. ACC 2019, 15-18 March, New Orleans, USA.

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