Abstract TP170: Persistently Elevated Factor VIII In Acute Ischemic Stroke Is Associated With Higher CRP, Lower Baseline NIHSS, And Longer Length Of Hospital Stay

Objective: We sought to determine the proportion of patients with elevated factor VIII (FVIII) levels whose FVIII levels remain elevated after the acute phase of stroke, and the patient characteristics that predict sustained elevation of FVIII levels.

Background: Factor VIII plays a major role in the fluid phase of blood coagulation. Elevated FVIII has been shown to increase risk of venous and arterial thrombosis. The importance of screening for elevated FVIII after a first thrombotic event especially acute ischemic stroke (AIS) has not been adequately investigated.

Design/Methods: We reviewed FVIII levels taken at baseline and follow-up in patients with AIS treated at our stroke center from July 2008 to June 2012. Elevated FVIII was defined as >150%. Baseline demographics, laboratory data, clinical course, outcomes, and time to follow-up were collected in patients with elevated FVIII at baseline and data was compared in patients who had normalized FVIII with patients whose FVIII remained elevated at least 7 days later.

Results: Repeat FVIII levels were available for 34/111 patients with elevated FVIII level with AIS. FVIII remained elevated in 68% after a median interval of 110 days. Factors associated with persistent elevation included higher baseline FVIII level (239 vs 185%, p=0.015), elevated CRP (73.3 vs 12.5%, p=0.008), lower baseline NIHSS (4 vs 8, p=0.046), and longer length of hospital stay (8 vs. 3, p=0.0063). Normalization of FVIII was associated with tPA use (54.5% vs 13%, p=0.016). No relationship was found between persistently elevated FVIII and baseline demographics, clinical course and outcomes.

Conclusion: Persistently elevated FVIII after AIS may be predicted by higher baseline levels and elevations in CRP. Despite worse baseline stroke severity, patient with normalization of FVIII had similar outcomes as those with persistent elevation, which may be explained by the higher use of tPA in the normalized group. The relevance of elevated FVIII in stroke is not well understood. Our preliminary results suggest elevations persist in the majority and may not merely represent an acute phase reactant.

Eradication of factor VIII inhibitors in patients with mild and moderate hemophilia A

In hemophilia A, up to 25% of new antifactor VIII (FVIII) inhibitory antibodies (inhibitors) occur in patients with mild or moderate disease. Once the inhibitor develops, options for management include observation, immune modulation, and immune tolerance induction (ITI). Currently, there is little data to guide a clinician's management decisions. In a case series, eight of the 26 subjects with mild or moderate hemophilia complicated by an inhibitor underwent ITI; two were successful, two were unsuccessful, and four were partially successful. In a systematic review of the literature, 12 of the 16 patients with mild or moderate hemophilia responded to rituximab for treatment to eradicate the inhibitor. To increase our understanding of treatment options for inhibitor eradication in patients with mild or moderate hemophilia A complicated by an inhibitor, a secondary analysis of clinical and treatment characteristics in a cohort of 36 patients with mild or moderate hemophilia A and inhibitor was undertaken. In multivariate analyses, rituximab alone (n = 6) and other immune-modulating treatments alone (n = 2) were significantly associated with an increased likelihood of inhibitor clearance [hazard ratio (HR) = 4.4 (95% CI = 1.06–20.03) and 10.21 (95% CI = 1.17–78.28), respectively], whereas ITI alone (n = 9) was not [HR = 1.35 (95% CI = 0.44–4.07)].

Abstract 3251: Relationship Between tPA and Factor VIII Levels in Patients with Acute Ischemic Stroke

Background: Factor VIII levels may be screened as part of a hypercoagulable work-up in patients with ischemic stroke. However, it is unknown how treatment with IV tPA may affect these levels during the acute phase of ischemic stroke.

Methods: From our prospective registry, we identified patients who presented with acute ischemic stroke to our stroke center between July 2008 and April 2011 and determined if factor VIII levels had been measured during the acute hospitalization. We compared mean factor VIII levels using independent sample t test in patients not treated with IV tPA to post-tPA treatment levels using independent samples t tests.

Results: Of the 72 patients who had factor VIII levels checked during admission, 25 (34.7%) received IV tPA. The mean factor VIII level was observed to be lower in patients who were treated with tPA (140.8 vs 180.5, p=0.048). Patients who experienced averted stroke (36%, 9/25) had significantly lower mean factor VIII level than patients who completed infarction on diffusion-weighted MRI (64%, 16/25) (132.7 vs 175.2, p=0.002). Of patients with post-tPA factor VIII levels, the mean factor VIII level of those whose samples were drawn within 24 hours of tPA were not different than the mean factor VIII level of those whose samples were drawn more than 24 hours after tPA (p=0.784).

Conclusion: Our observations found that factor VIII levels were lower in both patients treated with IV tPA and in patients with averted stroke. As factor VIII levels were drawn after thrombolytic therapy was administered, this raises the question of whether tPA lowers factor VIII levels or if factor VIII can serve as a potential surrogate marker for recanalization. Prospective studies examining factor VIII levels (1) before and after treatment with IV tPA and (2) in comparison to recanalization are needed to clarify this interesting observation.

Outcomes of mentored, grant-funded fellowship training in haemostasis /thrombosis: findings from a nested case-control survey study

Successful strategies by which to effectively recruit and retain academic subspecialists in benign haematology have not been established. To evaluate the effectiveness of a grant-funded, mentored fellowship with respect to retention and early career goals in haemostasis/thrombosis, we sought to compare outcomes for graduates of a grant-funded, mentored fellowship training programme in haemostasis/thrombosis [the National Hemophilia Foundation (NHF)-Baxter Clinical Fellowship Award] during conventional haematology/oncology fellowship training (cases), vs. their training peers who were graduates of conventional haematology/oncology fellowship training alone (controls), via a nested case-control survey study. Survey response rate was 85% (11/13) for cases and 90% (9/10) for controls. All respondents had pursued careers in academic haematology/oncology. Median (range) percent time spent in benign haematology postfellowship was 98% (70-100%) for cases vs. 0% (0-20%) for controls. Time spent in research was significantly greater among cases than controls (median 80% [range: 42-90%] vs. 55% [10-80%], respectively; P = 0.01). By years 3-4 postfellowship, median annual number of peer-reviewed publications was higher for cases than controls (3.5 vs. 1.0; P = 0.01). Cases were also more successful in grant funding (including K-awards). These data suggest that a grant-funded, mentored fellowship training programme in haemostasis/thrombosis may be superior to conventional haematology/oncology fellowship training alone with respect to outcomes of retention in clinical care/research, early-career grant funding and publication productivity.

Inhibitor development and successful immune tolerance in an HIV-infected patient with haemophilia A and after immune reconstitution with HAART

This is the case of a 28-year-old man with severe congenital haemophilia A, who had a relatively mild bleeding course during early childhood, with limited factor VIII (FVIII) exposure. He was infected with HIV before the age of 7 years, and demonstrated profound immunodeficiency from childhood, with very low CD4+ cell counts for more than a decade. Following initiation of highly active anti-retroviral therapy (HAART) and gradually increasing CD4+ cells, he presented for the first time with a high-titre inhibitor at age 26, despite over 1000 previous FVIII exposures. Subsequently, his inhibitor was successfully eradicated with a standard immune tolerance protocol. It is likely that the effects of chronic HIV infection on T-lymphocyte pathways, and the partial immune reconstitution resulting from HAART, led to this patient's unusual inhibitor course. Such a case serves to augment knowledge gained in animal studies about the immunobiology of FVIII inhibitors.