Effect of Chronic Blood Transfusions On Progression of Neurovascular Pathology in Pediatric Sickle Cell Patients.
Authors: Bishop Sarah , Matheus Gisele , Adams Robert J. , Jackson Sherron , Abboud Miguel R. , Kalpatthi Ram 
Published: October 2019

Abstract
Abstract 1510
Poster Board I-533

Background
Chronic blood transfusion is currently the standard of care for primary and secondary stroke prevention in children with sickle cell anemia (SCA) who have had an abnormal transcranial doppler (TCD) or cerebral vascular accident (CVA). However, the effect of chronic transfusion therapy on cerebral vasculopathy observed radiographically is not well known.

Methods
We reviewed SCA patients (Hb SS and Hb Sβ° thalassemia) at our institution who were on chronic blood transfusion for abnormal TCD or CVA. Baseline cerebral magnetic resonance imaging and angiography (MRI/MRA) scans performed at the time of abnormal TCD or initial CVA were compared with the most recent scans available for each patient. These scans were independently reviewed by a neuroradiologist who was blinded to patient and timing of scan. The scans were given scores based on a modified version of the previously published scoring system used in the STOP study, with higher scores corresponding to greater pathology.

Results
A total of 34 patients (53% male, 47% female) with a mean age of 6.47 years at the time of baseline MRI/MRA were studied. The median elapsed time from baseline MRI/MRA to the current scans was 7 years (range 2-13 years). Overall, patients had a mean change from the baseline MRI score of +0.76 and a mean change in MRA score of +1.03 indicating worsening vasculopathy (Table 1). There was a significant difference in mean change of MRI score between patients started on transfusion for a CVA compared to patients with abnormal TCD (+1.23 vs. -0.08, respectively: p = 0.001) [Table 1]. There was also a significant difference in mean change of MRA score between CVA and abnormal TCD patients (+1.54 vs. 0.08, respectively: p = 0.02) [Table 1]. Only 1 of 12 patients started on transfusion for an abnormal TCD showed worsening in MRA score. Furthermore, patients with CVA were more likely to have abnormal baseline MRA as well as worsening scores when compared to abnormal TCD patients (Figure 1). In addition, patients who had abnormal baseline MRA scores were more likely than those with normal baseline scores to have worsening cerebral vasculopathy (Figure 1).

Conclusion
Our study demonstrates that a subset of patients with SCA experience progression of cerebral vasculopathy despite chronic blood transfusion therapy. This is especially true for patients who had a baseline CVA or started with an abnormal baseline MRA. In contrast, chronic transfusion in patients with abnormal TCD not only prevents primary stroke, but also confers protection against the development and/or progression of cerebral vasculopathy. This effect appears to be real given our large cohort of patients with longer follow up as compared to previous studies. Nonetheless, further studies are needed to determine the effects of transfusions and the clinical significance of radiographic findings.

Disclosures
No relevant conflicts of interest to declare.