A Disastrous Week for Direct Oral Anticoagulants

Volume 19, Issue 3

The direct oral anticoagulants (DOACs) are profoundly safer than warfarin with respect to bleeding, particularly severe bleeding like intracerebral hemorrhage. As such, these agents are recommended as first-line for most types of venous thromboembolic diseases. The rare exceptions are selected conditions where warfarin still performs better, such as mechanical heart valve replacements or antiphospholipid antibody syndrome.

This week, we look at two more scenarios where warfarin may remain the preferred option.

Point 1: Transcatheter Aortic Valve Replacement

Transcatheter aortic valve replacement (TAVR) has emerged as a safer alternative to traditional (ie open heart) valve replacement, which has led to a significant increase in the number of these procedures being performed. Traditionally, patients undergoing TAVR are treated with antiplatelet therapy to prevent thrombotic complications.

Data regarding the use of DOACs after TAVR are derived from three randomized trials against either dual or single antiplatelet therapy. This week, a meta-analysis of these trials was published, which identified a numerically higher rate of both all-cause mortality (6.7% vs 4%) and non-cardiac mortality (2.9% vs 1.2%) with DOAC therapy. Rates of major bleeding or ischemic complications were not different between groups.

These findings suggest no incremental value of DOAC therapy over antiplatelet therapy in patients after TAVR surgery. The important caveat is this pertains only to patients without an indication for anticoagulant therapy, such as atrial fibrillation or history of venous thromboembolic disease.

Point 2: Rheumatic Heart Disease

Rheumatic heart disease remains a leading cause of atrial fibrillation in low- to moderate-income countries. This week, the INVICTUS trial evaluated the safety and efficacy of rivaroxaban vs warfarin in over 4500 patients with atrial fibrillation and rheumatic heart disease. Overall, the trial showed that patients assigned to rivaroxaban had a shorter mean survival time and a higher rate of death vs those on warfarin. There were no differences in the risk of bleeding between groups.

This trial demonstrates superiority of warfarin over DOAC therapy in patients with rheumatic heart disease, findings which carry significance given that most of these patients are in low-income countries where close monitoring of warfarin may be more difficult.