Unresponsiveness of Activated Partial Thromboplastin Time to Bivalirudin in Adults Receiving Extracorporeal Membrane Oxygenation

Activated partial thromboplastin time (aPTT) is the standard for monitoring bivalirudin but demonstrates a nonlinear response at higher drug concentrations. The objective of this study was to assess the relationship between bivalirudin dose and aPTT in patients receiving extracorporeal membrane oxygenation (ECMO) to determine a threshold where aPTT unresponsiveness occurs. Two hundred fourteen adults receiving bivalirudin during ECMO between 2018 and 2022 were included. Piecewise regression in a linear mixed effects model was used to determine a bivalirudin dose threshold of 0.21 mg/kg/hr for aPTT unresponsiveness. For doses of less than 0.21 mg/kg/hr (n = 135), every 0.1 mg/kg/hr dose increase led to an aPTT increase of 11.53 (95% confidence interval [CI] = 9.85-13.20) seconds compared to only a 3.81 (95% CI = 1.55-6.06) seconds increase when dose was greater than or equal to 0.21 mg/kg/hr (n = 79) (pinteraction < 0.001). In multivariable logistic regression, venovenous configuration (odds ratio [OR] = 2.83, 95% CI = 1.38-5.77) and higher fibrinogen concentration (OR = 1.22, 95% CI = 1.05-1.42) were associated with greater odds of unresponsiveness, whereas older age (OR = 0.79, 95% CI = 0.63-0.98), kidney dysfunction (OR = 0.48, 95% CI = 0.25-0.92), and a higher baseline aPTT (OR = 0.89, 95% CI = 0.82-0.97) were associated with lower odds. Alternative methods are necessary to ascertain bivalirudin's hemostatic impact when doses exceed 0.21 mg/kg/hr during ECMO.

Tranexamic Acid for Bleeding Management in Adult Patients on Extracorporeal Membrane Oxygenation

This study described the outcomes of patients receiving topical, nebulized, endobronchial, or systemic tranexamic acid (TXA) for bleeding events while on extracorporeal membrane oxygenation (ECMO). We performed a single-center case series including adult patients >18 years old supported on either venovenous (VV) or venoarterial (VA) ECMO from January 1, 2014, to April 21, 2021. The primary outcome was hemostatic control defined as a composite of initial cessation of therapeutic interventions to mitigate bleeding or resumption of anticoagulation if previously held. Secondary outcomes included changes in transfusion requirements and lysis at 30-minute (LY30) values, venous thromboembolism (VTE) events, and seizures. In total, 47 patients were included for full analysis. There were 19 patients with surgical bleeds, 18 patients with medical bleeds, and 10 patients with multiple bleeds. Overall, initial hemostatic control was achieved in 79%, 67%, and 90% of patients, respectively. Pre- and post-TXA transfusion requirements were not significantly different ( p = 0.2), although the intraindividual change in median LY30 was -5.1% compared with baseline (95% confidence interval [CI], -12.4% to -1.5%, p = 0.005). The occurrence of VTE and seizures was relatively low and similar among patient bleeding groups. Tranexamic acid provided initial hemostatic control in roughly three quarters of patients with bleeding events on ECMO and side effects were infrequent.

Assessment of bleeding risk in low-weight patients receiving prophylactic subcutaneous unfractionated heparin

BACKGROUND

Underweight patients may be at an increased risk of bleeding while receiving venous thromboembolism (VTE) prophylaxis. Additional evidence is needed to identify patient-specific factors associated with bleeding. The objective of the study was to describe the incidence and identify risk factors associated with bleeding in low-weight (⩽ 60 kg) adult patients receiving subcutaneous unfractionated heparin (SQH) for VTE prophylaxis.

METHODS

This was a single-center, retrospective, nested case-control study of low-weight patients receiving SQH for VTE prophylaxis for ⩾ 48 hours. Cases, patients with clinically relevant bleeding while receiving SQH, and controls, patients without a bleeding event, were matched in a 1:3 ratio for age, sex, primary service (surgical or medical), and time at risk of bleeding on SQH to determine factors associated with bleeding.

RESULTS

A total of 3761 patients met the inclusion criteria, of which 38 cases of clinically relevant bleeding were identified. The bleeding incidence was 1% at hospital day 6 and 2.8% at hospital day 14. Most patients in this study (69%) received SQH 5000 units three times daily. ICU admission at SQH start was associated with bleeding, OR 2.97 (95% CI 1.21-7.29).

CONCLUSION

Bleeding in low-weight patients on prophylactic SQH was uncommon. Patients admitted to the ICU at time of SQH start may be at a higher risk of bleeding. Further studies are needed to detect additional risk factors associated with bleeding and investigate the effects of reduced dosing in this population.

Extracorporeal cardiopulmonary resuscitation: A primer for pharmacists

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To describe the use of mechanical circulatory support in the setting of cardiac arrest and summarize pharmacists' role in extracorporeal cardiopulmonary resuscitation (ECPR).

SUMMARY

ECPR is increasingly used to reduce morbidity and improve mortality after cardiac arrest. ECPR employs venoarterial ECMO, which provides full circulatory perfusion and gas exchange in both adult and pediatric patients in cardiac arrest. After the emergency medicine team identifies potential candidates for ECPR, the ECMO team is consulted. If deemed a candidate for ECPR by the ECMO team, the patient is cannulated during ongoing standard cardiopulmonary resuscitation. A multidisciplinary team of physicians, nurses, perfusionists, pharmacists, and support staff is needed for successful ECPR. Pharmacists play a vital role in advanced cardiac life support (ACLS) prior to cannulation. Pharmacists intervene to make pharmacotherapy recommendations during ACLS, prepare medications, and administer medications as allowed by institutional and state regulations. Pharmacists also provide pharmacotherapy support in the selection of anticoagulation agents, ongoing vasopressor administration during ECMO cannulation, and the optimization of medication selection in the peri-ECPR period.

CONCLUSION

With the growing use of ECPR, pharmacists should be aware of their role in medication optimization during ECPR.

Hydroxocobalamin for Vasodilatory Hypotension in Shock: A Systematic Review With Meta-Analysis for Comparison to Methylene Blue

Hydroxocobalamin inhibits nitric oxide-mediated vasodilation, and has been used in settings of refractory shock. However, its effectiveness and role in treating hypotension remain unclear. The authors systematically searched Ovid Medline, Embase, EBM Reviews, Scopus, and Web of Science Core Collection for clinical studies reporting on adult persons who received hydroxocobalamin for vasodilatory shock. A meta-analysis was performed with random-effects models comparing the hemodynamic effects of hydroxocobalamin to methylene blue. The Risk of Bias in Nonrandomized Studies of Interventions tool was used to assess the risk of bias. A total of 24 studies were identified and comprised mainly of case reports (n = 12), case series (n = 9), and 3 cohort studies. Hydroxocobalamin was applied mainly for cardiac surgery vasoplegia, but also was reported in the settings of liver transplantation, septic shock, drug-induced hypotension, and noncardiac postoperative vasoplegia. In the pooled analysis, hydroxocobalamin was associated with a higher mean arterial pressure (MAP) at 1 hour than methylene blue (mean difference 7.80, 95% CI 2.63-12.98). There were no significant differences in change in MAP (mean difference -4.57, 95% CI -16.05 to 6.91) or vasopressor dosage (mean difference -0.03, 95% CI -0.12 to 0.06) at 1 hour compared to baseline between hydroxocobalamin and methylene blue. Mortality was also similar (odds ratio 0.92, 95% CI 0.42-2.03). The evidence supporting the use of hydroxocobalamin for shock is limited to anecdotal reports and a few cohort studies. Hydroxocobalamin appears to positively affect hemodynamics in shock, albeit similar to methylene blue.

Apixaban for Anticoagulation After Robotic Mitral Valve Repair

BACKGROUND

There is no consensus regarding postoperative anticoagulation after mitral valve repair (MVRep). We compared the outcomes of post-MVRep anticoagulation with apixaban compared to warfarin.

METHODS

We reviewed data of 666 patients who underwent isolated robotic MVRep between January 2008 and October 2019. We excluded patients who had conversion to sternotomy and those discharged without anticoagulation or on clopidogrel (n = 40). Baseline and intraoperative characteristics and antiplatelet/anticoagulation records were collected. In-hospital and post-discharge complications and overall survival were compared.

RESULTS

Among the 626 studied patients the median age was 58 years (interquartile range, 51-66), 71% were male, and 1% (n = 9) had atrial fibrillation. Eighty percent (n = 499) were discharged on warfarin and 20% on apixaban (n = 127). Almost all patients (126 of 127, 99%) in the apixaban group were also on aspirin at discharge, whereas in the warfarin group only 79% (n = 395) were also on aspirin at discharge. Baseline characteristics were similar, except that the apixaban group had more female patients (46 of 127, 36% vs 136 of 499, 27%, P = .047). There were no differences in in-hospital complications, including stroke. Readmission rate was higher in the apixaban group (15 of 127, 12% vs 30 of 499, 6%, P = .02), driven mostly by postoperative atrial fibrillation (6 of 127 [5%] vs 5 of 499 [1%], respectively; P = .01). There was no difference in other complications (including bleeding and thromboembolic events), or overall mortality within 3 years. Exclusion of patients who did not receive aspirin at discharge did not affect the results.

CONCLUSIONS

Anticoagulation with apixaban after minimally invasive robotic MVRep is safe and has similar rates of bleeding and thromboembolism compared to patients treated with warfarin.

A Single-Center Bleeding Comparison of Warfarin Plus Aspirin or Clopidogrel Following Coronary Artery Bypass Grafting and Surgical Valve Replacement

The optimal antithrombotic therapy following combined coronary artery bypass graft (CABG) and surgical valve replacement (SVR) surgery remains unclear. The aim of this single-center, retrospective cohort study was to assess the safety and effectiveness of a vitamin K antagonist (VKA) plus either aspirin or clopidogrel in patients following combined CABG and SVR. The primary endpoint was the occurrence of bleeding within six months. The secondary endpoint was the occurrence of CV death, stroke, acute coronary syndrome (ACS), or valve dysfunction. Outcomes were identified by pre-specified ICD codes. A total of 629 patients were included in the analysis, with 583 patients receiving aspirin and 46 patients receiving clopidogrel. Bleeding occurred in 1.7% of patients receiving aspirin and in 0% of patients receiving clopidogrel (p  =  0.99). CV death, stroke, ACS, or valve dysfunction occurred in 3.1% of patients receiving aspirin and 4.3% of patients receiving clopidogrel (p  =  0.65). In this study, there were no differences in the safety or effectiveness of a VKA plus either aspirin or clopidogrel following combined CABG and SVR.

Hemostatic Management in Extracorporeal Membrane Oxygenation

The use of extracorporeal membrane oxygenation (ECMO) for acute cardiac and/or respiratory failure has grown exponentially in the past several decades. Systemic anticoagulation is a fundamental element of caring for ECMO patients. Hemostatic management during ECMO walks a fine line to balance the risk of safe and effective anticoagulant delivery to mitigate thromboembolic complications and minimizing hemorrhagic sequelae. This review discusses the pharmacology, monitoring parameters, and special considerations for anticoagulation in patients requiring ECMO.

Safety Comparison of Monotherapy Aspirin to Dual Antiplatelet Therapy Following Coronary Artery Bypass Surgery

Background

Dual antiplatelet therapy (DAPT) is recommended over single antiplatelet therapy (SAPT) in patients following coronary artery bypass grafting (CABG). The compilation of evidence has focused on the efficacy of DAPT to limit risk of graft occlusion, however the safety, especially in the on-pump CABG population, is less well described. The aim of this study was to assess the safety of DAPT versus SAPT after on-pump CABG.

Methods

This was a single-center, retrospective cohort analysis of adult patients following isolated on-pump CABG between January 2012 and December 2019 not on oral anticoagulation at discharge. The primary endpoint was occurrence of a composite bleeding event identified by pre-specified ICD codes. Secondary endpoints consisted of 30-day and 1-year mortalities along with individual bleeding components.

Results

Of the 2341 patients included 1250 patients were in the SAPT arm and 1091 patients in the DAPT arm. The study populations differed by age, prior MI, PAD, and CHF status/stage. Bleeding events occurred in a total of 70 patients (3.0%), with 36 patients (2.9%) in the SAPT arm and 34 patients (3.1%) in the DAPT arm (P = .74). 30-day (SAPT 0.7% vs DAPT 0.4%) and 1-year (SAPT 3.3% vs DAPT 2.3%) mortality were not significantly different between groups. The most frequent bleed event was in the gastrointestinal tract.

Conclusion

In this study, DAPT was not associated with an increase in composite bleeding compared to SAPT. This study could reduce the barrier to prescribing of DAPT given previous efficacy data.

Intensive Care Unit Sedation Practices at a Large, Tertiary Academic Center

BACKGROUND

Sedatives are frequently administered in an ICU and are often dependent on patient population and ICU type. These differences may affect patient-centered outcomes.

OBJECTIVE

Our primary objective was to identify differences in sedation practice among three different ICU types at an academic medical center.

METHODS

This was a retrospective cross-sectional study of adult patients (≥18 years) requiring a continuous sedative for ≥6 h and admitted to a medical ICU, surgical ICU, and medical/surgical ICU at a single academic medical center in Rochester Minnesota from June 1, 2018 to May 31, 2020. We extracted baseline characteristics; sedative type, dose, and duration; concomitant therapies; and patient outcomes. Summary statistics are presented.

RESULTS

A total of 2154 patients met our study criteria (1010 from medical ICU, 539 from surgical ICU, 605 from medical/surgical ICU). Propofol was the most frequently used sedative in all ICU settings (74.1% in medical ICU, 53.8% in surgical ICU, 68.9% in medical/surgical ICU, and 67.5% in all ICUs). The mortality rate was highest in the medical/surgical ICU (40.2% in medical ICU, 26.0% in surgical ICU, 40.7% in medical/surgical ICU, and 36.8% in all ICUs). 90.7% of all patients required mechanical ventilation (92.9% in medical ICU, 88.5% in surgical ICU, and 89.1% in medical/surgical ICU). Overall, patients spent more time in light sedation than deep sedation, 75% versus 10.3%, during their ICU admission. Patients in the medical ICU spent a greater proportion of time positive for delirium than the other ICU settings (35.7% in medical ICU, 9.8% in surgical ICU, and 20% in medical/surgical ICU). Similar amounts of opioids (morphine milligram equivalents) were used during the continuous sedative infusion between the three settings.

CONCLUSIONS

We observed that patients in the medical ICU spent more time deeply sedated with multiple agents which was associated with a higher proportion of delirium.

Comparison of Warfarin to Dual Antiplatelet Therapy Following Transcatheter Aortic Valve Replacement

INTRODUCTION

Dual antiplatelet therapy (DAPT) was the initial antithrombotic regimen of choice following transcatheter aortic valve replacement (TAVR). Subsequent identification of subclinical valve thrombosis in high-risk patients has questioned whether warfarin should be used as an alternative to DAPT for some patients.

OBJECTIVE

The aim of this study was to compare thromboembolic events, bleeding, and all-cause mortality between DAPT and warfarin following TAVR.

METHODS

This was a single-center, retrospective review of TAVR patients who received DAPT or warfarin following TAVR between 2008 and 2018. The primary endpoint was occurrence of thromboembolic events during the hospital stay and 1-year follow-up, while secondary endpoints included bleeding and all-cause mortality.

RESULTS

Of the included 764 patients, 193 received DAPT and 571 received warfarin. The median Society of Thoracic Surgeons (STS) Predicted Risk of Mortality (PROM) scores were 8.3% for the DAPT group and 6.5% for the warfarin group. The primary endpoint occurred 30 times (3.9%) during the study timeframe. No differences in thromboembolic events between the DAPT and warfarin groups were found (4.14% vs. 3.85%; p = 0.857), and there was no difference in bleeding (6.22% vs. 5.08%; p = 0.544) or risk of mortality (hazard ratio 0.59, 95% confidence interval 0.33-1.06; p = 0.076).

CONCLUSIONS

In this study, warfarin had similar effectiveness and safety, compared with DAPT, for antithrombotic management post-TAVR. For patients whom the provider deemed anticoagulation is indicated, our data suggest warfarin is a well-tolerated option following TAVR in intermediate- and high-risk STS score patients.

Physical Therapy and Sedation While on Extracorporeal Membrane Oxygenation for COVID-19-Associated Acute Respiratory Distress Syndrome

OBJECTIVES

This study aimed to determine whether patients on extracorporeal membrane oxygenation (ECMO) with coronavirus disease 2019 (COVID-19) achieved lower rates of physical therapy participation and required more sedation than those on ECMO without COVID-19.

DESIGN

Retrospective, observational, matched-cohort study.

SETTING

Bicenter academic quaternary medical centers.

PARTICIPANTS

All adults on ECMO for severe COVID-19-associated acute respiratory distress syndrome (ARDS) during 2020 and matched (matched 1:1 based on age ± 15 years and medical center) adults on ECMO for ARDS not associated with COVID-19.

INTERVENTIONS

Observational only.

MEASUREMENTS AND MAIN RESULTS

Measurements were collected retrospectively during the first 20 days of ECMO support and included daily levels of physical therapy activity, number of daily sedation infusions and doses, and level of sedation and agitation (Richmond Agitation and Sedation Score). During the first 20 days of ECMO support, the 22 patients who were on ECMO for COVID-19-associated ARDS achieved a similar proportion of days with active physical therapy participation while on ECMO compared to matched patients on ECMO for non-COVID-19 ARDS (22.5% v 7.5%, respectively; p value 0.43), a similar proportion of days with Richmond Agitation and Sedation Score ≥-2 while on ECMO (47.5% v 27.5%, respectively; p value 0.065), and a similar proportion of days with chemical paralysis while on ECMO (8.4% v 18.0%, respectively; p value 0.35).

CONCLUSIONS

The results of this matched cohort study supported that sedation requirements were not dramatically greater and did not significantly limit early physical therapy for patients who had COVID-19-associated ARDS and were on venovenous extracorporeal membrane oxygenation (VV-ECMO) versus those without COVID-19-associated ARDS who were on VV-ECMO.

Vasopressin in vasoplegic shock: A systematic review

BACKGROUND

Vasoplegic shock is a challenging complication of cardiac surgery and is often resistant to conventional therapies for shock. Norepinephrine and epinephrine are standards of care for vasoplegic shock, but vasopressin has increasingly been used as a primary pressor in vasoplegic shock because of its unique pharmacology and lack of inotropic activity. It remains unclear whether vasopressin has distinct benefits over standard of care for patients with vasoplegic shock.

AIM

To summarize the available literature evaluating vasopressin vs non-vasopressin alternatives on the clinical and patient-centered outcomes of vasoplegic shock in adult intensive care unit (ICU) patients.

METHODS

This was a systematic review of vasopressin in adults (≥ 18 years) with vasoplegic shock after cardiac surgery. Randomized controlled trials, prospective cohorts, and retrospective cohorts comparing vasopressin to norepinephrine, epinephrine, methylene blue, hydroxocobalamin, or other pressors were included. The primary outcomes of interest were 30-d mortality, atrial/ventricular arrhythmias, stroke, ICU length of stay, duration of vasopressor therapy, incidence of acute kidney injury stage II-III, and mechanical ventilation for greater than 48 h.

RESULTS

A total of 1161 studies were screened for inclusion with 3 meeting inclusion criteria with a total of 708 patients. Two studies were randomized controlled trials and one was a retrospective cohort study. Primary outcomes of 30-d mortality, stroke, ventricular arrhythmias, and duration of mechanical ventilation were similar between groups. Conflicting results were observed for acute kidney injury stage II-III, atrial arrhythmias, duration of vasopressors, and ICU length of stay with higher certainty of evidence in favor of vasopressin serving a protective role for these outcomes.

CONCLUSION

Vasopressin was not found to be superior to alternative pressor therapy for any of the included outcomes. Results are limited by mixed methodologies, small overall sample size, and heterogenous populations.

Safety and Efficacy of Oral Anticoagulants for Atrial Fibrillation in Patients After Bariatric Surgery

Anticoagulation management is challenging in bariatric surgery patients, due to altered gastrointestinal anatomy and potentially reduced absorption. Few studies have evaluated clinical outcomes in this population. The objective of this study was to compare the efficacy and safety of oral anticoagulants in patients with and without a history of bariatric surgery. A retrospective, matched cohort study was conducted, utilizing data from the OptumLabs Data Warehouse. Patients ≥18 years old, with nonvalvular atrial fibrillation (NVAF), and treated with an oral anticoagulant between January 1, 2010 and December 31, 2018 were included. Outcomes were compared between bariatric and nonbariatric surgery patients. Secondary analysis compared warfarin to the direct oral anticoagulants (DOAC) in the bariatric cohort. The primary efficacy outcome was the rate of ischemic stroke and systemic embolism and the primary safety outcome was major bleeding. A total of 1,673 bariatric surgery and 155,619 nonbariatric surgery patients were identified. There was no significant difference in the rate of ischemic stroke or systemic embolism (0.83 vs 1.32 per 100 person years; Hazard ratio [HR] 0.62, 95% confidence interval [CI] 0.31 to 1.22; p = 0.17) or major bleeding (5.30 vs 4.87 per 100 person years; HR 1.05, 95% CI 0.80 to 1.37; p = 0.73) between bariatric and nonbariatric surgery patients. In bariatric surgery patients alone, efficacy and safety were similar with warfarin compared with the DOACs. Results of this study suggest that bariatric surgery patients are not at an increased thrombotic or bleeding risk when using oral anticoagulants for NVAF. DOACs may be a reasonable alternative to warfarin.

Tirofiban in Suspected Left Ventricular Assist Device Pump Thrombosis

Antithrombotic optimization with a glycoprotein IIb/IIIa inhibitor has been used for the treatment of suspected pump thrombosis, but available literature with tirofiban is lacking. This study aims to describe the use of tirofiban for suspected pump thrombosis. This was a single-center cohort study of left ventricular assist device patients who received tirofiban for the treatment of suspected pump thrombosis from January 1, 2016 to July 31, 2017. Tirofiban was initiated at 0.1 μg/kg/min in patients with normal renal function and subsequent dose adjustments for altered renal function or history of bleeding were employed. Success was defined as resolution of lactate dehydrogenase back to patients' known baseline. Fourteen patients were included for 16 total instances of tirofiban use during the time period. Tirofiban was continued for a median of 5 days (range: 0.3-35 days). Successful treatment was achieved in 12 of the 16 tirofiban uses (75%). Seven bleeding events occurred while on therapy, two major and five minor. This study showed a majority of patients achieved success with tirofiban for suspected pump thrombosis. For patients who are not current candidates for pump exchange or transplant, tirofiban may be considered a therapeutic medical management option.

Warfarin-Induced Rapid Rise in INR Post-Cardiac Surgery Is Not Associated With Increased Bleeding Risk

Background: Post-cardiac surgery bleeding can have devastating consequences, and it is unknown if warfarin-induced rapid international normalized ratio (INR) rise during the immediate postoperative period increases bleed risk. Objective: To determine the impact of warfarin-induced rapid-rise INR on post-cardiac surgery bleeding. Methods: This was a single-center, retrospective chart review of post-cardiac surgery patients initiated on warfarin at Mayo Clinic Hospital, Rochester. Patients were grouped based on occurrence or absence of rapid-rise INR (increase ≥1.0 within 24 hours). The primary outcome compared bleed events between groups. Secondary outcomes assessed hospital length of stay (LOS) and identified risk factors associated with bleed events and rapid rise in INR. Results: During the study period, 2342 patients were included, and 56 bleed events were evaluated. Bleed events were similar between rapid-rise (n = 752) and non-rapid-rise (n = 1590) groups in both univariate (hazard ratio [HR] = 1.22; P = 0.594) and multivariable models (HR = 1.24; P = 0.561). Those with rapid-rise INR had longer LOS after warfarin administration (discharge HR = 0.84; P = 0.0002). The most common warfarin dose immediately prior to rapid rise was 5 mg. Risk factors for rapid-rise INR were low body mass index, female gender, and cross-clamp time. Conclusion and Relevance: This represents the first report to assess warfarin-related rapid-rise INR in post-cardiac surgery patients and found correlation to hospital LOS but not bleed events. Conservative warfarin dosing may be warranted until further research can be conducted.

Comparison of In-Hospital Bleeding and Cardiovascular Events with High-Dose Bolus Tirofiban and Shortened Infusion to Short-Duration Eptifibatide as Adjunctive Therapy for Percutaneous Coronary Intervention

Potent platelet inhibition is one of the most important medical interventions to prevent ischemic complications during and after percutaneous coronary intervention (PCI). Practice has evolved with the introduction of potent oral P2Y₁₂ inhibitors that provide quick, effective platelet inhibition, and the need for routine glycoprotein IIb/IIIa inhibitors (GPIs) has decreased. Additionally, a shorter duration of GPI infusion has been shown to be safe with adequate oral antiplatelet loading, but clinical outcome data are limited to eptifibatide. This single-center, retrospective cohort study analyzed in-hospital outcomes for patients who received adjunctive GPI therapy for PCI before and after an institution-wide switch to high-dose bolus tirofiban with shortened infusion from short-duration eptifibatide. The primary end point was a composite in-hospital outcome of major and minor bleeding and cardiovascular events (death, myocardial infarction, coronary artery bypass grafting, ischemic stroke, and target vessel revascularization). Secondary end points included bleeding and cardiovascular event types. A total of 357 and 446 patients received eptifibatide and tirofiban, respectively, from February 1, 2014 through September 30, 2017. Thirty five eptifibatide and 46 tirofiban patients experienced an in-hospital composite event (9.8% vs 10.3%, p = 0.81). There was no difference found between in-hospital bleeding (6.4% vs 5.4%, p = 0.52) or cardiovascular events (5.6% vs 6.5%, p = 0.60) with the use of eptifibatide or tirofiban, respectively. Multivariable analysis showed that patients with transradial access or an indication of unstable angina were less likely to experience an in-hospital composite event (OR 0.30 and 0.19, respectively, p <0.001 for both). In conclusion, the use of high-dose bolus tirofiban with shortened infusion versus short-duration eptifibatide was not associated with an increase of in-hospital bleeding or cardiovascular events.

Comparison of Warfarin Requirements in Post-cardiac Surgery Patients: Valve Replacement Versus Non-valve Replacement

INTRODUCTION

Anticoagulation with warfarin affects approximately 140,000 post-cardiac surgery patients every year, yet there remains limited published data in this patient population. Dosing remains highly variable due to intrinsic risk factors that plague cardiac surgery candidates and a lack of diverse literature that can be applied to those who have undergone a cardiac surgery alternative to heart valve replacement (HVR). In the present study, our aim was to compare the warfarin requirements between HVR and non-HVR patients.

METHODS

This was a single-center, retrospective study of post-cardiac surgery patients initiated on warfarin at Mayo Clinic Hospital, Rochester, from January 1st, 2013 to October 31st, 2016. The primary outcome was the maintenance warfarin dose at the earliest of discharge or warfarin day 10 between patients with HVR and non-HVR cardiac surgeries.

RESULTS

A total of 683 patients were assessed during the study period: 408 in the HVR group and 275 in the non-HVR group. The mean warfarin maintenance doses in the HVR and non-HVR groups were 2.55 mg [standard deviation (SD) 1.52] and 2.43 mg (SD 1.21), respectively (adjusted p = 0.65). A multivariable analysis was performed to adjust for gender, age, body mass index and drug interactions.

CONCLUSIONS

This was the largest study to evaluate warfarin dose requirements in post-cardiac surgery patients and is the first to compare warfarin requirements between HVR and non-HVR patients during the immediate post-operative period. Both groups had similar warfarin requirements, which supports expanding the initial warfarin dosing recommendations of the 9th edition Chest guideline to include non-HVR patients as well as HVR patients.

Therapeutic drug monitoring of mexiletine at a large academic medical center

Introduction:

The therapeutic trough range for mexiletine (0.8–2 mcg/mL) was largely established in the setting of arrhythmia prophylaxis following myocardial infarction.

Objective:

Describe the usage patterns of serum mexiletine concentrations and the impact of these concentrations on mexiletine dosing in modern practice for ventricular arrhythmia treatment.

Methods:

A single-center, retrospective analysis was conducted using the electronic medical record to identify serum mexiletine concentrations drawn between December 2004 and December 2014. The primary endpoint was the incidence of mexiletine concentrations drawn as troughs. Secondary outcomes included the incidence of mexiletine concentrations that prompted a dose change, association between adverse events and elevated concentrations, and association between baseline characteristics and mexiletine concentrations.

Results:

A total of 237 individual concentrations were included for analysis with 109 (46.0%) drawn appropriately as trough concentrations. Only 31 (13.1%) of the 237 concentrations drawn prompted a dose change. Mexiletine was primarily used for the treatment of ventricular arrhythmias (96.2%), and 108 (45.6%) concentrations were drawn in an effort to assess efficacy. The median concentration was statistically different between patients with and without an adverse event (0.8 vs 0.7 mcg/mL, respectively; p = 0.017), but may not represent a clinical significance. Patients with hepatic dysfunction had higher median concentrations compared to those without hepatic dysfunction (1.30 vs 1.07 mcg/mL; p = 0.01).

Conclusion:

Mexiletine concentrations are often drawn at inappropriate times and seldom influence a dose change. This study suggests that routine monitoring of mexiletine concentrations may not be necessary; however, therapeutic drug monitoring may be considered in patients with hepatic dysfunction or to confirm mexiletine absorption in patients where this represents a concern.

Levetiracetam Pharmacokinetics in a Patient Receiving Continuous Venovenous Hemofiltration and Venoarterial Extracorporeal Membrane Oxygenation

Levetiracetam is a first-line therapy for seizures in critically ill patients because of its clinical efficacy, minimal drug interactions, and wide therapeutic window. The primary mechanism of levetiracetam clearance is renal, and the drug has a low molecular weight. It is hydrophilic and exhibits minimal protein binding. Thus it is expected that levetiracetam will be removed by continuous venovenous hemofiltration (CVVH), with limited clearance by venoarterial extracorporeal membrane oxygenation (ECMO). We describe the case of a 67-year-old man who was admitted to the cardiovascular surgery intensive care unit after cardiac arrest and initiation of venoarterial ECMO. His course was complicated by multiorgan dysfunction including acute renal failure requiring CVVH. On hospital day 6, intravenous levetiracetam, at a loading dose of 2000 mg followed by a maintenance dose of 1000 mg every 12 hours, was initiated for new-onset seizures. The volume of distribution was 0.65 L/kg, and clearance was measured with peak (ranging from 26.5-39.8 μg/ml) and trough (ranging from 13.9-18.2 μg/ml) concentrations. Elimination half-life ranged from 8.7-10.1 hours. Renal dysfunction reduces levetiracetam clearance, and dosage reductions are recommended to prevent accumulation. Current CVVH dosing recommendations are based on predicted removal without clinical data. The volume of distribution and clearance in this case were similar to those of a normal healthy patient. Based on these results, we recommend considering an initial levetiracetam dose of 1000 mg every 12 hours for patients receiving CVVH, with dosage adjustments based on therapeutic drug monitoring.