Feasibility of rapid measurement of Rivaroxaban plasma levels in patients with acute stroke

Plasma levels of Rivaroxaban (RivLev) might be useful to guide therapeutic decisions in patients with acute stroke under Rivaroxaban. A prerequisite for the potential clinical usefulness is their rapid availability in emergency situations. Single-center explorative analysis from the Novel-Oral-Anticoagulants-in-Stroke-Patients registry (NOACISP, cinicaltrials. gov: NCT02353585). We included consecutive patients with acute ischemic or hemorrhagic stroke under Rivaroxaban (last intake < 48 h) in which RivLev determined by an automated anti-factor Xa based chromogenic assay (Hyphen-Biomed, France) are available. Primary endpoint was the turnaround time (TAT), defined as time from registration of the blood sample in the lab to first result published. Furthermore, we studied, whether TAT is influenced by (1) on-and off-hour-measurements and (2) early versus later patient arrival (cut-off: 270 min after symptom onset). Thirty-eight patients met the eligibility criteria (mean age 77 years, 44 % female). TAT was 34 min (IQR 29-65 min). TATs were similar for on-(n=14; median 34 min; IQR 30-56 min) and off-hours TATs (n=24; median 35 min; IQR 29-75 min) as well as for early (n=16; median 33 min; IQR 30-40 min) and late patient arrival (n=22, median 34 min, IQR 28-58 min; all nonsignificant.). Taking into account RivLev in the decision process about the use of intravenous thrombolysis, three patients received intravenous thrombolysis on an individualized basis, none of them with bleeding complications. Emergency measurement of RivLev among patients with acute stroke is available within a median of 34 min and therefore feasible for ED use. Due to the rapid availability, further research to evaluate the role of RivLev in order to guide acute treatment decisions is warranted.