Ventricular Assist Device Anti-Factor Xa (VAD ANTIX) Monitoring Study: a Prospective Randomized Feasibility Trial

Not Applicable

Completed

• Conditions: Thrombosis, LVAD; Anti-factor Xa; Left Sided Heart Failure; Anticoagulant Therapy; Left Ventricular Assist Device; aPTT; Gastro Intestinal Bleeding; Heparin
• Interventions: Device: aPTT guided heparin management; Device: Anti-factor Xa guided heparin management

• Registration Number: NCT03143569
• Lead Sponsor: Washington University School of Medicine

Brief Summary

This study evaluates two different methods for monitoring a patient's anti-clotting \[heparin\] therapy after they receive a heart pump implant \[left ventricular assist device -LVAD\]. One method tests for how long it takes the patient's blood to clot and uses that to determine if they are on the right dose of heparin. The other method uses a more direct measure of how much heparin is in the blood. The hypothesis is that the method that more directly measures how much heparin is in the patient's blood will provide better medical results for the patient's care after they have the heart pump implant. To that end, the investigators are conducting this feasibility trial to establish the logistics associated with the implementation of these heparin monitoring approaches.

Detailed Description

Heart failure is a medical condition that is on the rise in the US and is associated with an enormous cost of $30 billion in healthcare expenses. People with heart failure may be treated with an LVAD that is connected to their heart and helps it pump the blood from the left side of the heart into the blood vessels that delivers blood to the body. These devices can be used to treat heart failure for the long term or they can be used while a patient waits for a heart transplant. In either case, the use of these devices is increasing.

One of the primary risks associated with LVADs are those related to blood clotting. Maintenance of the LVAD depends on preventing blood clots especially right after the surgery that puts them in place. This requires putting patients with LVADs on blood thinners and then monitoring the blood thinner levels carefully so that they don't have problems with bleeding too easily or, on the other hand, forming blood clots if they aren't on the right dose of blood thinners. Excessive bleeding - called hemorrhaging - is the more common problem after surgery and half of all patients that receive an LVAD will require a blood transfusion within the first 30 days after they receive the device. A laboratory test that measures how quickly blood clots is used to determine if the patient has the right amount of blood thinners. The current standard test is called "activated partial thromboplastin time \[aPTT\]." There are problems with the reliability of this test because it reacts with other elements in the blood. Alternately, there is a test that more directly measures the amount of heparin blood thinner rather than coagulation time and may be more reliable than aPTT called anti-factor Xa \[anti-Xa\].

The investigators have developed process diagrams that show steps for making decisions \[called nomograms\] that tell a nurse or doctor how to manage the heparin levels using test results from the aPTT test or the anti-Xa test; however, both tests will be performed at each decision time point, but the care team will only be told the results from the testing to which their patient is assigned.

The purpose of this feasibility study is to establish feasibility of using the two nomograms to determine which provides the optimal clinical information for improving patients' outcomes that have had LVADs placed.

Potential subjects will be recruited prior to their surgery and may decline to participate anytime before or after the surgery takes place. Subjects will be randomized to the aPTT nomogram or the anti-Xa nomogram. If they withdraw consent, they will receive the aPTT standard of care monitoring. The study procedures are performed by the clinical care team. Clinicians will be trained to use the nomograms.

Study Timeline

• Study First Submitted: 2017-04-20
• Study First Submitted QC: 2017-05-03
• Study First Posted: 2017-05-08
• Study Start: 2017-05-20
• Primary Completion: 2018-07-12
• Study Completion: 2018-07-12
• Results First Submitted: 2019-09-11
• Status Verified: 2020-02
• Results First Submitted QC: 2020-02-17
• Last Update Submitted: 2020-02-17
• Results First Posted: 2020-02-25
• Last Update Posted: 2020-02-25

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 20

Inclusion Criteria

1. 18 years of age and older
2. Implantation with HeartMate II® or HeartWare®, LVAD at Barnes Jewish Hospital

Read More

Exclusion Criteria

1. Unable to receive heparin-based therapy
2. Hypercoagulable disorders [factor V Leiden, Antithrombin deficiency, Protein C deficiency, Antiphospholipid antibodies or other thrombophilia]
3. Incarceration
4. Pregnancy or breastfeeding

Read More

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
aPTT nomogram	aPTT guided heparin management	aPTT guided heparin management
aPTT nomogram	Anti-factor Xa guided heparin management	aPTT guided heparin management
Anti-factor Xa nomogram	aPTT guided heparin management	Anti-factor Xa guided heparin management
Anti-factor Xa nomogram	Anti-factor Xa guided heparin management	Anti-factor Xa guided heparin management

Primary Outcome Measures

Name	Time	Method
Nomogram Feasibility	14 days of heparin therapy	Questionnaires evaluating pragmatic application of nomograms. Question 5: I often had to seek clarification from a coworker, pharmacist, NP, or MD regarding the nomogram instructions.
Success of Nomogram	14 days of heparin therapy	Amount of time sustained in therapeutic anticoagulation range

Secondary Outcome Measures

Name	Time	Method
Time to Therapeutic Dose	14 days of heparin therapy	Amount of time needed to achieve therapeutic dose from heparin initiation
Nomogram Concordance	14 days of heparin therapy	Compare heparin dosing success between aPTT and anti-factor Xa nomograms. If aPTT was within therapeutic range of nomogram AND anti-factor Xa was within range in therapeutic nomogram, then paired values were deemed "concordent". Similiarly if both aPTT AND anti-factor Xa were above therapeutic range OR both below therapeutic range, then paired valued were deemed "concordent". Otherwise values deemd "discordant"
Dosing Changes	14 days of heparin therapy	Number of dosing changes during heparin therapy until first therapeutic

Trial Locations

Locations (1)

Washington University in St Louis School of Medicine; 🇺🇸 Saint Louis, Missouri, United States