Clinical and Hemostatic Characteristics of Patients With Ventricular Assist Device Thrombosis

Purpose: Rotational thromboelastometry (ROTEM), a method for hemostasis testing in whole blood, has been used to manage and adjust anti-coagulation therapy in post VAD implant patients. Performing ROTEM prior to implant may shed light on important hemostatic characteristics in patients that develop pump thrombosis (PT) post VAD implantation. Methods: All VAD implantations at our institution between 2008 through 2015 were included in the analysis. Suspected PT was defined as a pump-related malfunction and hemolysis and definitive PT required visualized thrombus at the time of explant. A subset of patients underwent ROTEM prior to post-implant. The patients' EXTEM CT (latency time of clot formation once start reagent has been added to a patient's blood) was measured and analyzed. Results: 139 patients were implanted during the study time (21% female). 28 patients had suspected or definitive pump thrombosis (25%). There were no significant differences found in mean age, gender, etiology of heart failure, or medications (see Table 1). Patients with PT were more likely to have public insurance (P = .03). There was no significant difference in patients' pre-implant EXTEM CT between non-PT and PT (mean 56 and 62, respectively, P = .10). Using Friedman's ANOVA, the ROTEM EXTEM CT value increased over the pre-implant through 3 month post-implant interval (P = .006, n = 15). This was not looked at separately for patients who experienced a thrombotic event vs patients who did not due to low sample size. Conclusion: Other than insurance type, there are no easily identifiable clinical or pre-implant risk factors associated with PT. Furthermore, there was no significant difference pre-implant ROTEM EXTEM CT between the two groups. It is notable that there is a significant increase of patients' CT over the 3 month interval, regardless of a diagnosis of thrombosis. Further studies are needed to explore the alterations in hemostatics in VAD patients who experience PT.