Abstract Background and aims Delayed cerebral ischemia (DCI) is a major cause of morbidity after aneurysmal subarachnoid hemorrhage (aSAH) and is thought to result from impaired microvascular physiology. Currently, there are no biomarkers for DCI. Transcranial Doppler (TCD) is commonly used to assess vasospasms as surrogate marker for the diagnosis of DCI, yet is limited in predicting DCI. The velocity curvature index (VCI) is a novel TCD-based metric quantifying the morphology of cerebral blood flow velocity (CBFV) waveforms, also in response to changes in the distal microvasculature. Therefore, we hypothesized that VCI predicts DCI. Methods Prospective, repeated TCD examinations were performed in aSAH patients during the first two weeks after ictus. Bilateral middle cerebral artery (MCA) CBFV was measured at three depths for ≥30 seconds. VCI was calculated from individual beat waveforms to generate a representative waveform. Lower VCI values indicate signal dampening. Mixed-effects models were used to identify factors associated with VCI. Receiver operating characteristic (ROC) analysis evaluated prediction of DCI. Results Thirty patients were included; seven developed DCI. Distal MCA CBFV were associated with lower VCI (β = −0.17, SE = 0.08, p = 0.044). In linear mixed-effects analysis, distal MCA VCI was significantly lower in patients who developed DCI (β = −1.07, p = 0.038). Baseline distal MCA VCI, age, and sex predicted DCI with excellent accuracy (AUC 0.91, 95% bootstrap percentile CI 0.79–1.00). Conclusions Impaired VCI in the distal MCA preceded DCI in our cohort and may serve as a non-invasive, bedside biomarker for predicting DCI in aSAH patients. Conflict of interest H Schenck: nothing to declare, C van Craenenbroeck: nothing to declare, E Gommer: nothing to declare, W Mess: nothing to declare, M Aries: nothing to declare, M Veldeman; nothing to declare, O Teernstra: nothing to declare, J Dings; nothing to declare, I de Ridder; nothing to declare, Y Temel: nothing to declare, R Haeren: nothing to declare
Schenck et al. (2026) studied this question.