Black hole sign under anticoagulant therapy: A retrospective comparison of warfarin and direct oral anticoagulants.

Background and purpose: Direct oral anticoagulants (DOAC) have rapidly replaced warfarin. Intracerebral hemorrhage (ICH) is known to be one of the most severe side effects of anticoagulant drugs. The black hole (BH) sign is reportedly a valid radiological sign for predicting hematoma expansion in acute ICH. Here, we hypothesized that the frequency of BH signs might differ between warfarin and DOAC treatment, and critically evaluated the clinical value of the BH sign in acute ICH under warfarin versus DOAC therapy.

Materials and methods: Patients with acute ICH under anticoagulant therapy were enrolled. Hematoma volumes were measured by ABC/2. Radiologists blinded to the clinical information determined the presence or absence of the BH sign on CT images. This study defined a more than 12.5 ml increase in hematoma volume as cases with "expanded hematoma".

Results: We analyzed 111 acute ICH patients under anticoagulant therapy. Among them, 21 patients were treated with antagonists in this cohort. Multivariate logistic regression analysis revealed that the presence of ventricular perforation (p=0.02; adjusted odds ratio (OR): 3.51, 95% confidence interval (CI): 1.32 - 10.2) and the BH sign (p<0.01; adjusted OR: 4.86, 95% CI: 1.73 - 14.3) were significantly different between expanded and non-expanded hematoma cases. Comparison of hematoma volume and the presence of the BH sign between warfarin and DOAC cases indicated significant differences in maximum hematoma volume (p=0.03) and presence of the BH sign (p<0.01). The increase in hematoma volume was significantly greater when the BH sign was present under warfarin therapy (p=0.05). In contrast, the increase in hematoma volume did not differ between cases with and without the BH sign in patients under DOAC therapy (p=0.14) CONCLUSIONS: The BH sign is a useful radiological signature to predict the expansion of acute ICH under anticoagulant therapy. ICH under warfarin tended to present the BH sign more frequently than that under DOAC. The results also showed that the BH sign is more reliable under warfarin than under DOAC therapy in ICH patients.

Abbreviations: AF = atrial fibrillation; BH = black hole; DOAC = direct oral anticoagulants; HU = Hounsfield Unit; ICH= intracerebral hemorrhage.