Comparison of Managing Factor Xa Inhibitor to Unfractionated Heparin Transitions by aPTT Versus a Treatment Guideline Utilizing Heparin Anti-Xa Levels.

BACKGROUND: There are inadequate data on the optimal strategy for transitioning factor Xa inhibitors (FXai; apixaban, rivaroxaban) to unfractionated heparin (UFH) infusions. OBJECTIVE: In patients transitioning from an FXai to an UFH infusion, this study compared the safety and efficacy of monitoring UFH infusions using an activated partial thromboplastin time (aPTT) titration scale versus utilizing an UFH-calibrated anti-Xa titration scale aided by a novel institutional guideline. METHODS: A retrospective cohort analysis was conducted on adult patients transitioning from an FXai to an UFH infusion at 2 medical centers from June 1, 2018, to November 1, 2020. One institution utilized aPTT while the other institution primarily used UFH-calibrated anti-Xa. The primary endpoint was a composite of death, major bleeding, or new thrombosis during the hospitalization with a planned noninferiority analysis. Secondary outcomes were also collected including the amount and duration of UFH administered between cohorts. RESULTS: The incidence rate of the primary composite endpoint was 6.3% in the anti-Xa group and 11% in the aPTT group (P < 0.001 for noninferiority, P = 0.138 for superiority) meeting noninferiority criteria. No statistical differences were seen in new thrombosis, major bleeding, or any bleeding. CONCLUSION AND RELEVANCE: This represents the first report of a comparison between aPTT versus anti-Xa monitoring in relation to clinical outcomes for patients transitioning from an FXai to an UFH infusion. A transition guideline primarily utilizing an UFH-calibrated anti-Xa assay appears to be a safe alternative to aPTT monitoring and can aid facilities in the management of patients during these complex transitions.

Utilization of apixaban anti-Xa levels in transition from apixaban to warfarin in a patient with chronic renal dysfunction.

PURPOSE: The effect of apixaban on anti-factor Xa (anti-Xa) assays and international normalized ratio (INR) complicates transitions between anticoagulant agents. When switching from apixaban to warfarin, the recommendation is to begin both a parenteral anticoagulant and warfarin at the time of the next apixaban dose and to discontinue the parenteral agent when the INR is in an acceptable range. This proves challenging in renal dysfunction, as continued presence of apixaban contributes to both a prolonged effect on the INR and continued therapeutic levels of anticoagulation. SUMMARY: This case describes the transition of apixaban to warfarin in a patient with acute on chronic kidney disease and recent deep vein thrombosis, utilizing chromogenic apixaban anti-Xa assays to assess the level of anticoagulation and avoid unnecessary parenteral anticoagulation. CONCLUSION: Utilization of apixaban anti-Xa levels aided in the transition from apixaban to warfarin in a patient with chronic renal failure and avoided need for parenteral bridging therapy.

Use of specific anti-Xa levels in acute kidney injury to transition patients from oral factor Xa inhibitors to i.v. heparin infusion.

PURPOSE: This case series presents 3 patients with acute kidney injury taking apixaban or rivaroxaban and transitioning to a heparin infusion. SUMMARY: Case 1 was a 78-year-old man admitted with respiratory failure, acute decompensated heart failure, and acute kidney injury. He was taking apixaban for atrial flutter. He was transitioned to an i.v. heparin infusion and had 2 consecutive heparin antifactor-Xa levels greater than 2 units/mL. Heparin was held and resumed about 36 hours later when the apixaban anti-Xa level was less than 50 ng/mL. Case 2 was a 55-year-old man admitted with acute kidney injury, taking apixaban for a recent deep vein thrombosis. Apixaban anti-Xa levels were monitored and i.v. heparin was initiated when the level was less than 100 ng/mL, about 56 hours after the last apixaban dose. Case 3 was a 64-year-old woman admitted with sepsis and acute kidney injury taking rivaroxaban for pulmonary embolism, which occurred 2 weeks prior to admission. Rivaroxaban anti-Xa levels were monitored and i.v. heparin was initiated about 36 hours after the last dose when the level was less than 100 ng/mL. The management strategy did not lead to any thrombotic outcomes; however, 1 patient experienced bleeding. CONCLUSION: Specific anti-Xa levels for rivaroxaban and apixaban appeared to be helpful in the transition of 3 patients to unfractionated heparin infusions in the setting of acute kidney injury. These levels provided enhanced, individualized care and likely helped avoid over and under anticoagulation.

Successful use of laboratory monitoring to facilitate an invasive procedure for a patient treated with dabigatran.

PURPOSE: A case in which novel and traditional laboratory markers were successfully used to determine surgical intervention timing in an elderly patient receiving dabigatran for atrial fibrillation is reported. SUMMARY: An 86-year-old woman who was taking dabigatran for atrial fibrillation suffered a right femoral neck fracture requiring surgical intervention. Dabigatran was withheld once the patient was admitted to the hospital, and the pharmacy inpatient anticoagulation management team was consulted for guidance on determining appropriate scheduling of surgical intervention with regard to the time since her most recent dabigatran dose to minimize bleeding complications. The team recommended delaying surgery, as dabigatran clearance would likely take 3-5 days and an ecarin chromogenic assay (ECA) dabigatran value of <50 ng/mL would be desirable before surgical intervention. During her hospitalization, novel and traditional laboratory markers for dabigatran, such as ECA value, activated partial thromboplastin time, thrombin time, and prothrombin time, were measured and followed closely to determine the best time to perform surgical intervention to minimize bleeding risk. Renal dysfunction likely delayed dabigatran elimination in the patient and may have led to potential accumulation of dabigatran. The patient ultimately had to wait 5 days after the last dabigatran dose for surgical intervention. CONCLUSION: Coagulation assay monitoring for dabigatran, with emphasis on an ECA dabigatran concentration of <50 ng/mL, was used to assess safety regarding bleeding risk before a nonemergent surgical procedure in an 86-year-old woman with a right femoral neck fracture.