Faculty Bibliography

The need for therapeutic drug monitoring of direct oral anticoagulants (DOACs) remains an area of clinical equipoise. Although routine monitoring may be unnecessary given predictable pharmacokinetics in most patients, there may be altered pharmacokinetics in those with end organ dysfunction, such as those with renal impairment, or with concomitant interacting medications, at extremes of body weight or age, or in those with thromboembolic events in atypical locations. We aimed to assess real-world practices in situations in which DOAC drug-level monitoring was used at a large academic medical center. A retrospective review of the records of patients who had a DOAC drug-specific activity level checked from 2016 to 2019 was included. A total of 119 patients had 144 DOAC measurements (apixaban (n = 62) and rivaroxaban (n = 57)). Drug-specific calibrated DOAC levels were within an expected therapeutic range for 110 levels(76%), with 21 levels (15%) above the expected range and 13 levels (9%) below the expected range. The DOAC levels were checked in the setting of an urgent or emergent procedure in 28 patients (24%), followed by renal failure in 17 patients (14%), a bleeding event in 11 patients (9%), concern for recurrent thromboembolism in 10 patients (8%), thrombophilia in 9 patients (8%), a history of recurrent thromboembolism in 6 patients (5%), extremes of body weight in 7 patients (5%), and unknown reasons in 7 patients (5%). Clinical decision making was infrequently affected by the DOAC monitoring. Therapeutic drug monitoring with DOACs may help predict bleeding events in elderly patients, those with impaired renal function, and in the event of an emergent or urgent procedure. Future studies are needed to target the select patient-specific scenarios where monitoring DOAC levels may impact clinical outcomes.

The oral factor Xa inhibitors (OFXAi) apixaban and rivaroxaban are increasingly utilized for the treatment of venous thromboembolism (VTE) with recommended initial higher dose 7- and 21-day lead-in regimens, respectively. In patients receiving initial parenteral anticoagulation, it remains unknown if the full recommended higher dose OFXAi lead-in regimens are warranted, or if days can be subtracted. We aimed to describe when clinicians may deviate from recommended lead-in durations and evaluate clinical outcomes in these scenarios. This is a retrospective, observational study of patients 18 years or older who were treated with rivaroxaban or apixaban for acute pulmonary embolism (PE) or symptomatic proximal deep vein thrombosis (DVT) that received parenteral anticoagulation for at least 24 h before transitioning to the OFXAi. Among our cohort of 171 patients with acute VTE who received parenteral anticoagulation for a median of 48 h, 134 (78%) were prescribed a full OFXAi lead-in and 37 (22%) were prescribed a reduced lead-in. Patients in the reduced lead-in group were older with more cardiac comorbidities and antiplatelet use. There were four recurrent thromboembolic events within 3 months, two in the reduced lead-in group and two in the full lead-in group (5% vs. 2%, p = 0.206). Bleeding within 3 months occurred in 9 (5%) patients, with 6 events occurring in the reduced lead-in group and 3 events in the full lead-in group (16% vs. 2%, p = 0.004). Prescribing patterns of OFXAi lead-in therapy duration are variable in patients receiving initial parenteral anticoagulation. Larger cohorts are needed to better define the safety and efficacy of lead-in reduction.

The use of acute mechanical circulatory support (MCS) has increased over the last decade. For patients with left-ventricular failure, an Impella^® (Abiomed, Danvers, MA) may be used to improve cardiac output. The purpose of this study is to describe Impella^® anticoagulation patterns and evaluate the safety and effectiveness of our protocol. This is a retrospective review of all adult patients who required at least 24 h of Impella^® support and received a heparin-based purge solution. In total, 109 patients were included in the final analysis. The most common indication for Impella^® device insertion was cardiogenic shock (76%) with the remaining patients receiving a device for a high-risk procedures; typically coronary artery bypass grafting or percutaneous coronary intervention. A total of 9 thrombotic events occurred among 8 (7%) patients and 50 bleeding events occurred among 43 (39%) patients, with the most common classification being BARC 3a (60%). A univariate analysis revealed that patients were more likely to bleed if they were less than 65 years old, had an indication of cardiogenic shock for Impella^®, inserted the device peripherally, were on dual antiplatelet therapy, or had an intra-aortic balloon pump prior to Impella^® insertion, the latter of which was confirmed with a multivariate analysis (OR 2.5 [1.072-5.830]; p = 0.034). For those monitored by anti-Xa, the presence of two or more values greater than 0.40 IU/mL was a risk factor for bleeding (p = 0.037). Our study identifies risk factors for bleeding in patients receiving temporary MCS with an Impella^®.

Background : The activated partial thromboplastin time (aPTT) and anti-factor Xa (anti-Xa) test are often used as surrogate markers of heparin's effects, though anti-Xa may be preferred due to less variability and closer relation to heparin's activity in the body. The antithrombotic and hemostatic therapy oversight group at NYU Langone Health (NYULH) implemented a nurse-titrated protocol, utilizing anti-Xa to titrate and monitor time in therapeutic range with heparin. Aims : To evaluate adherence to the nurse-driven continuous infusion unfractionated heparin protocol and assess time to therapeutic anti-Xa, median time in therapeutic range, and clinical outcomes including bleeding and thrombotic events. Methods : This was a retrospective chart review. Adult patients (>18 years old) who received heparin based on nurse-driven titration protocol between March 2019 and June 2019 at NYULH were included. Patients that received heparin for less than 24 hours, had an interruption in heparin for more than 12 hours, or received a direct oral anticoagulant (DOAC) prior to heparin initiation were excluded. Data collection included baseline characteristics, relevant concomitant medications, heparin administration including bolus dose, infusion rate, length of therapy, time within therapeutic range, bleeding events, and thrombotic events. The primary outcome was adherence to the protocol. Secondary outcomes included time within therapeutic range, thrombotic or bleeding events. Results : Adherence to the protocol, defined as deviation of not more than 25% of protocol elements, including but not limited to adequate bolus dose, correct body weight used, time to first anti-Xa, and correct adjustment (units/kg) in heparin dose based on anti-Xa was observed 85% of the time, with the majority of dose titrations occurring by nursing, per protocol in 82% of patients. Therapeutic anti-Xa levels were achieved at a median of 30 hours into IV UFH therapy. Conclusions : It remains a challenge to achieve a stable goal anti-Xa level within 24 hours of heparin initiation