Thromboembolic stroke in patients with a HeartMate-II left ventricular assist device - the role of anticoagulation

Abstract

Background and purpose: It is unknown what the optimal anticoagulant level is to prevent thromboembolic stroke in patients with left ventricular assist device (LVAD) support. We aimed to evaluate the relation between coagulation status and the occurrence of thromboembolic stroke in HeartMate-II LVAD assisted patients. Methods: Thirty-eight consecutive patients with a HeartMate-II LVAD were included. Coagulation status was classified according to INR and aPTT ratio at: 1) the moment of first thromboembolic stroke; and 2) during the two weeks preceding the first thromboembolic stroke to assess long-term coagulation status. In patients without stroke, coagulation status was determined just before heart transplant, VAD explantation or death, whichever came first, and at two weeks preceding these surrogate endpoints. Based on coagulation status, patients were divided in two groups: Group I (reference group) was defined as INR below 2 and aPTT ratio below 1.5; Group II (adequate anticoagulation) as INR above 2 or aPTT ratio above 1.5. Logistic regression analysis was performed to assess the odds ratio for developing stroke for patients with adequate anticoagulation compared to the reference Group. Results: Thromboembolic stroke occurred in six (16 %) patients, none within 2 weeks after LVAD implantation. Considering coagulation status at the time of event, patients in coagulation Group II had no decreased risk for thromboembolic stroke (OR 0.78; 95 % CI 0.12-5.0). Results for coagulation status 2 weeks prior of event could not be calculated as all six strokes occurred in Group II. Conclusion: In our experience anticoagulation within predefined targets is not associated with a reduced thromboembolic stroke risk in patients with a HeartMate-II LVAD on antiplatelet therapy. However, no firm statement about the effect of either anticoagulant or antiaggregant therapy can be made based on our study. A larger randomized study is needed to support the hypothesis that there may be no additional benefit of coumarin or heparin therapy compared with antiplatelet therapy alone.