Lower Post-TAVR Mortality Seen on DOAC vs VKA When OAC Indicated

Ted Bosworth

July 20, 2021

Following a transcatheter aortic valve replacement (TAVR), direct oral anticoagulants (DOACs) are preferable to vitamin K antagonists (VKAs) in patients who are candidates for oral anticoagulants, according to data drawn from a large multicenter French TAVR registry.

When oral anticoagulation is appropriate following TAVR, such as in patients with atrial fibrillation, "DOACs are associated with improved survival and lower incidence of bleeding, compared to VKA," reported a team of investigators led by Martine Gilard, MD, PhD, director of interventional cardiology, Brest (France) University Hospital Center.

The comparison, using propensity score matching, is not definitive, but it might be the best data currently available to support DOACs over VKA until a randomized trial is completed, according to Gilard, senior author of the newly published study.

Asked in an interview if DOACs should now be used preferentially after TAVR when patients are indicated for oral anticoagulation, Gilard replied, "My answer is yes."

Of more than 24,000 TAVR patients in the French TAVI and FRANCE2 multicenter registries, which are linked to the French single-payer claims database (SNDS), 8,962 (36.4%) received an oral anticoagulant following their procedure. Of these, 2,180 (24.3%) received a DOAC and the remaining received VKA.

By linking data from the registries to the SNDS, outcomes were tracked. Propensity matching was employed to control for differences in baseline characteristics, including age, body mass index, functional class, diabetes, comorbidities, and past medical history.

On the primary endpoint of mortality at the end of 3 years, the rates were 35.6% and 31.2% for VKA and DOACs, respectively. This translated in a 37% greater hazard ratio for death among those treated with VKA (< .005).

The rate of major bleeding, a secondary endpoint, was also higher (12.3% vs. 8.4%) and significantly different (HR, 1.65; < .005) for VKA versus DOACs. The rates of ischemic stroke, acute coronary syndrome, and hemorrhagic stroke were all numerically higher in patients treated with VKA than DOACs, although none of these differences reached statistical significance.

Residual Confounding Cannot Be Discounted

"The large number of events allowed for taking into account a higher number of potential confounders with appropriate statistical power," according to the authors. However, they acknowledged that residual confounding cannot be eliminated by propensity matching and conceded that prospective data are needed for a definitive comparison.

In an accompanying editorial, Daniele Giacoppo, MD, a cardiologist at Alto Vicentino Hospital, Santorso, Italy, enlarged on this point. In addition to the inherent limitations of retrospective data, he also noted that data from other studies addressing the same question have been inconsistent.

Of these studies, he pointed to the ATLANTIS trial, presented 2 months ago at the annual meeting of the American College of Cardiology. This study failed to show an advantage for the DOAC apixaban over VKA in TAVR patients for the primary composite outcome of time to death, myocardial infarction, systemic emboli, valve thrombosis, or major bleeding. Although this study was not limited to patients with an indication for oral anticoagulants, Giacoppo pointed out that there was no advantage, even among the subgroup of patients who did have an indication.

Data Are Supportive in Absence of Trial Results

In general, Giacoppo agreed that the French registry are generally supportive of DOACs over VKA in TAVR patients with an indication for oral anticoagulation, but he cautioned that blanket statements are difficult. He anticipates better information from a randomized trial called ENVISAGE-TAVI AF, which is comparing edoxaban with VKA following TAVR in atrial fibrillation patients who have an indication for oral anticoagulation, but he indicated that some individualization of choice will be needed among those high or low relative risks of thrombotic events or bleeding.

"The concerns related to DOACs after TAVR are most confined to patients without an indication for oral anticoagulation," Giacoppo said in an interview. In patients with an indication, "oral anticoagulation alone without antithrombotic therapy significantly reduced the risk of bleeding" in several studies, he added, citing in particular the POPular TAVI trial.

Issues about when to employ — or not employ — both oral anticoagulation and antithrombotic therapy based on such factors as bleeding risk remain unresolved, but "in aggregate, waiting for additional high-quality data, the use of a DOAC in patients with an indication for oral anticoagulation who underwent TAVR seems to be safe," Giacoppo said. He thinks that the "higher predictability of DOACS compared to vitamin K antagonists might translate into lower bleeding rates over time in a real-world, unselected population."

Benefit-to-Risk Ratio Requires Attention

A similar concern about balancing risks and benefits of oral anticoagulation in TAVR patients with an indication for oral anticoagulation was emphasized by Ron Waksman, MD, associate director, division of cardiology, MedStar Washington (D.C.) Hospital Center.

"The TAVR population is elderly in general and so are at high risk for bleeding with any additional anticoagulation," Waksman said. He cited data that bring into question the utility of using a DOAC in TAVR patients without an additional indication for anticoagulation, but he believes DOACs do make sense in those who were on and had an indication for a DOAC even before TAVR.

Patients who had atrial fibrillation or another indication "should continue to take the DOAC after TAVR. This population can be assumed to have less bleeding risk as they are vetted as safe for DOACs before their TAVR procedure," he said.

Although mortality was the primary endpoint of the French registry evaluation, it is the bleeding risk that is a dominant concern, according to Romain Didier, MD, PhD, the first author of this study who performed this work in collaboration with Gilard.

"We really believe that VKA use in real life after TAVR, even with INR monitoring, is associated with a higher risk of bleeding as compared to DOACs," he said. It is for this reason that "we currently use DOACs as a first choice in patients who require anticoagulant after TAVR."

Gilard, Didier, and Giacoppo reported no potential conflicts of interest. Waksman reported financial relationships with Amgen, AstraZeneca, Boston Scientific, Cardioset, Cardiovascular Systems, Chiesi, MedAlliance, Medtronic, and Pi-Cardia.

J Am Coll Cardiol Intv. Published online July 14, 2021. Abstract, Editorial

This article originally appeared on MDEdge.com.

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