Direct oral anticoagulant (DOAC) – Cardiology MCQ – Answer

Direct oral anticoagulant (DOAC) – Cardiology MCQ – Answer

Which of the following is not an indication for direct oral anticoagulant (DOAC) like dabigatran – Correct answer: d) Mechanical prosthetic mitral valve

Mechanical prosthetic valve is a highly thrombogenic situation and DOAC is not enough to prevent it. As Vitamin K antagonists act on multiple levels in the coagulation cascade, they are powerful enough to prevent thrombosis on mechanical prosthetic valves. RE-ALIGN trial comparing warfarin and dabigatran in mechanical heart valve replacement (mitral or aortic) was terminated prematurely due to excess thromboembolic and bleeding events in those on dabigatran [1].

Though vitamin K antagonists like warfarin provide excellent protection against thromboembolic complications [2] in patients with mechanical prosthetic valves, they need regular coagulation monitoring (prothrombin time with international normalized ratio: PT-INR). They have multiple food and drug interactions which can change the INR and lead to INR out of therapeutic range and hence the time in therapeutic range (TTR).

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References

1. Eikelboom JW, Connolly SJ, Brueckmann M, Granger CB, Kappetein AP, Mack MJ, Blatchford J, Devenny K, Friedman J, Guiver K, Harper R, Khder Y, Lobmeyer MT, Maas H, Voigt JU, Simoons ML, Van de Werf F; RE-ALIGN Investigators. Dabigatran versus warfarin in patients with mechanical heart valves. N Engl J Med. 2013 Sep 26;369(13):1206-14.
2. Cannegieter SC, Rosendaal FR, Briet E. Thromboembolic and bleeding complications in patients with mechanical heart valve prostheses. Circulation 1994;89:635-641.