Whilst offering overall benefits, implanted mechanical devices have several associated risks. One of the more prevalent risks is thrombosis, caused by the interaction of the blood with components of the device itself. To mitigate this risk, anticoagulants have always been used alongside LVAD therapy. Antiplatelet therapies are also used postoperatively to help aid thrombus risk reduction.
These therapies are life-long and are an integral part of device implantation. Due to its ready availability and easy reversibility, Warfarin is the most commonly used anticoagulant in LVAD patients. Aspirin is the most prescribed antiplatelet for similar reasons.
Despite the increased bleeding risk - up to 1.5 to 2 times - associated with the concurrent use of anticoagulant and antiplatelet therapy, their combination in LVAD patients has been justified to further reduce thrombotic activity.
Advances in current LVAD technology and design have led to a significant reduction in pump thrombosis rates. These results have prompted queries over the necessity of aspirin in the management of LVAD patients.
Small-scale studies and individual patient cases have indicated that the cessation of antiplatelet regimens does not always adversely impact thrombotic events.
To further investigate this indication the ARIES HM3 (Antiplatelet Removal and Hemocompatibility Events with the HeartMate 3 Pump) double-blind, randomised, placebo-controlled study was initiated. The study was the largest to date investigating the removal of antiplatelet therapy in LVAD patients, yielding ground-breaking results.
A total of 589 HeartMate 3 patients were included in the trial with the participants split into two study groups. The first continued with anticoagulant and antiplatelet therapy (aspirin). The second group continued only with anticoagulant therapy, then taking a placebo instead of aspirin. The findings demonstrated that patients in the placebo group had improved safety compared to the combination group.
The study concluded that:
"avoidance of aspirin as part of an antithrombotic regimen, which includes VKA, is not inferior to a regimen containing aspirin, does not increase thromboembolism risk, and is associated with a reduction in bleeding events."
These findings, coupled with insights from other studies, will be integral to shaping future LVAD protocols.
Whilst it is imperative to acknowledge that the MiniVAD™ is not a fully magnetically levitated device, extensive research has been conducted to mitigate the risk of thrombosis and reduce blood damage. Calon is committed to developing a pump that requires a minimal antithrombotic regime.