Background and purpose: It is unknown how little flow velocity improvement is necessary to achieve recanalization and clinical recovery. We sought to investigate which flow velocity parameter was associated with complete recanalization/reperfusion and neurological improvement in patients receiving reperfusion therapies.
Methods: Patients with proximal intracranial occlusions were treated with systemic or intra-arterial tissue plasminogen activator within 6 hours from symptom onset. Consecutive peak systolic and end-diastolic (EDV) velocities were measured during continuous transcranial Doppler monitoring. Recanalization was graded with Thrombolysis in Brain Ischemia grades. Neurological and functional outcomes were assessed by the National Institutes of Health Stroke Scale and modified Rankin Scale scores.
Results: Of 36 patients (mean age 57 + or - 19 years, median National Institutes of Health Stroke Scale 15 points, interquartile range 9), 13 (36%) achieved complete recanalization and those had greater EDV increase during transcranial Doppler monitoring (15 + or - 11 cm/s versus 6 + or - 10 cm/s; P=0.001). Peak systolic velocity increase with complete recanalization was 25 + or - 11 cm/s (versus 20 + or - 25 cm/s with partial recanalization/persisting occlusion; P=0.123). Neurological improvement at 24 hours positively correlated to EDV increase (Spearman r=0.337, P=0.044) but not to peak systolic velocity (r=0.197, P=0.250). EDV increase at the end of monitoring was higher in patients with favorable functional outcome at 3 months (13 + or - 13 cm/s versus 4 + or - 8 cm/s; P=0.021). After adjustment for potential confounders, including age, stroke risk factors, and baseline stroke severity, a 10-cm/s increase in EDV was independently associated with a 3-point decline in the National Institutes of Health Stroke Scale score at 24 hours from baseline (95% CI: 0 to 5; P=0.045).
Conclusions: A modest increase in the EDV as opposed to peak systolic velocity is associated with complete recanalization/reperfusion, early neurological improvement, and favorable functional outcome. Diastolic flow augmentation may represent a novel target for development of reperfusion therapies.