EComment. Thrombus strikes back: Promising role of thromboelastography for thromboembolic risk prediction in HeartMate II recipients

Abstract

Heart failure is a major public health problem representing the ultimate stage of various cardiovascular diseases. Currently left ventricular assist devices (LVADs) have been increasingly used for the management of patients with end-stage heart failure. Every year approximately 4000 LVADs are implanted in the US; approximately three-quarters of these are HeartMate II. The HeartMate II is a small, continuous flow, rotary, left-sided heart pump approved by the FDA for bridge to transplantation in cardiac transplant candidates with the advantages of smaller size, less invasive surgical implantation procedure and low dose anticoagulation requirement. However, according to a recently published paper based on pooled data from 895 patients with the HeartMate II LVAD device, the thrombosis rate occurring early after implantation is nearly four times higher than rates seen in pre-approval clinical trials [1]. Karimi et al. reported that thrombelastography (TEG) guided antiplatelet therapy reduces the late onset bleeding rate in HeartMate II recipients [2]. Thrombelastography is a superb coagulation test which has the advantage of combining multiple data obtained from various coagulation tests into a single read-out. Furthermore, TEG gives information about platelet function, clot strength, and fibrinolysis which other coagulation tests cannot provide. Prompted by the manuscript of Karimi et al, we speculate that TEG could be a useful test for predicting thrombotic risk in HeartMate II recipients. Haemostasis occurs with orchestrated function of platelets, clotting factors and vascular endothelium. Thrombelastography provides an effective and convenient means of monitoring the entire coagulation cascade which can traditionally be measured via several conventional tests. Thrombelastography is a promising test for predicting thrombosis [3]. It demonstrates a hypercoagulable state that is not detected by prothrombin time or partial thromboplastin time. Conventional coagulation tests cannot assess factors predicting thromboembolic risk such as clot strength and degree of clot dissolution [4]. In summary, HeartMate II recipients have surprisingly high device thrombosis rates. Since these patients are also at risk for bleeding complications, anticoagulation should be carefully titrated. The art of LVAD-implanted patient management is weighing the risk between haemorrhagic and thromboembolic events. Thrombelastography may guide clinicians while making challenging decisions. Conflict of interest: none declared