Abstract

The success of mechanical circulatory support (MCS) hinges on appropriate anticoagulation. The delicate balance between clotting and bleeding remains challenging to achieve consistently in the post-operative period and requires an individualised approach, especially in patients with acquired warfarin resistance including those with latent malignancies who have failed different anticoagulant regimens. Anecdotal studies and a recent randomised controlled trial have shown that dabigatran is not an alternative to warfarin in this setting.^{1 2}

Predicting clotting or bleeding risk can be informative but published data remain scarce. Whereas the CHA₂DS₂-VASc risk score has not been demonstrated to predict thromboembolism in patients with left ventricular assist device (LVAD), the HAS-BLED score may have potential for predicting bleeding.³ Although data from a pharmacogenetic study suggested that the AA genotype of VKORC1 (−1639 G>A; allele frequency of 12%) may confer advantage to appropriate warfarin anticoagulation as demonstrated by surrogate markers including decreased time to target international normalised ratio,⁴ there remains no one-size-fits-all strategy that is reliable and scalable.

Perioperatively, the use of intravenous heparin remains the mainstay of anticoagulation at most centres that implant LVADs and/or utilise short-term MCS, and activated clotting time remains the most commonly used measure of anticoagulation. Alternatives to intravenous heparin include bivalirudin and argatroban, but data on their comparative efficacy and safety in MCS are limited. Moreover, these agents may not be available in national health systems of many Asian countries due to costs and, possibly, a difference in the epidemiology of heparin-induced thrombocytopaenia warranting their use.