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

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

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT03143569
Acronym
VAD-ANTIX
Enrollment
20
Registered
2017-05-08
Start date
2017-05-20
Completion date
2018-07-12
Last updated
2020-02-25

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Anticoagulant Therapy, Anti-factor Xa, aPTT, Gastro Intestinal Bleeding, Heparin, Left Sided Heart Failure, Left Ventricular Assist Device, Thrombosis, LVAD

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.

Interventions

DEVICEaPTT guided heparin management

post-surgical implantation anti-coagulation therapy to prevent clotting in ventricular assist device.

DEVICEAnti-factor Xa guided heparin management

post-surgical implantation anti-coagulation therapy to prevent clotting in ventricular assist device

Sponsors

Washington University School of Medicine
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Caregiver)

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No

Inclusion criteria

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

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

Design outcomes

Primary

MeasureTime frameDescription
Nomogram Feasibility14 days of heparin therapyQuestionnaires evaluating pragmatic application of nomograms. Question 1: The current heparin nomogram using (aPTT or anti-Xa depending on group) monitoring is easy to follow.
Success of Nomogram14 days of heparin therapyAmount of time sustained in therapeutic anticoagulation range

Secondary

MeasureTime frameDescription
Nomogram Concordance14 days of heparin therapyCompare 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 Changes14 days of heparin therapyNumber of dosing changes during heparin therapy until first therapeutic
Time to Therapeutic Dose14 days of heparin therapyAmount of time needed to achieve therapeutic dose from heparin initiation

Countries

United States

Participant flow

Participants by arm

ArmCount
aPTT Nomogram
aPTT guided heparin management aPTT guided heparin management: post-surgical implantation anti-coagulation therapy to prevent clotting in ventricular assist device. Anti-factor Xa guided heparin management: post-surgical implantation anti-coagulation therapy to prevent clotting in ventricular assist device
10
Anti-factor Xa Nomogram
Anti-factor Xa guided heparin management aPTT guided heparin management: post-surgical implantation anti-coagulation therapy to prevent clotting in ventricular assist device. Anti-factor Xa guided heparin management: post-surgical implantation anti-coagulation therapy to prevent clotting in ventricular assist device
10
Total20

Baseline characteristics

CharacteristicaPTT NomogramAnti-factor Xa NomogramTotal
Age, Categorical
<=18 years
0 Participants0 Participants0 Participants
Age, Categorical
>=65 years
1 Participants2 Participants3 Participants
Age, Categorical
Between 18 and 65 years
9 Participants8 Participants17 Participants
Age, Continuous53.3 years
STANDARD_DEVIATION 12.3
50.5 years
STANDARD_DEVIATION 13.4
51.9 years
STANDARD_DEVIATION 12.6
Ethnicity (NIH/OMB)
Hispanic or Latino
0 Participants0 Participants0 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
10 Participants10 Participants20 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants
INTERMACS Profile score less than 410 Participants10 Participants20 Participants
Region of Enrollment
United States
10 participants10 participants20 participants
Sex: Female, Male
Female
3 Participants5 Participants8 Participants
Sex: Female, Male
Male
7 Participants5 Participants12 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
0 / 100 / 10
other
Total, other adverse events
0 / 100 / 10
serious
Total, serious adverse events
2 / 103 / 10

Outcome results

Primary

Nomogram Feasibility

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.

Time frame: 14 days of heparin therapy

ArmMeasureGroupValue (NUMBER)
aPTT NomogramNomogram FeasibilitySurveys Completed136 Surveys
aPTT NomogramNomogram FeasibilityAffirmative Responses45 Surveys
Anti-factor Xa NomogramNomogram FeasibilitySurveys Completed112 Surveys
Anti-factor Xa NomogramNomogram FeasibilityAffirmative Responses22 Surveys
p-value: 0.018Chi-squared
Primary

Nomogram Feasibility

Questionnaires evaluating pragmatic application of nomograms. Question 4: When my patient is on the heparin nomogram, I follow the dosing and monitoring instructions exactly.

Time frame: 14 days of heparin therapy

ArmMeasureGroupValue (NUMBER)
aPTT NomogramNomogram FeasibilitySurveys Completed136 Surveys
aPTT NomogramNomogram FeasibilityAffirmative Responses136 Surveys
Anti-factor Xa NomogramNomogram FeasibilitySurveys Completed112 Surveys
Anti-factor Xa NomogramNomogram FeasibilityAffirmative Responses112 Surveys
p-value: 1Fisher Exact
Primary

Nomogram Feasibility

Questionnaires evaluating pragmatic application of nomograms. Question 1: The current heparin nomogram using (aPTT or anti-Xa depending on group) monitoring is easy to follow.

Time frame: 14 days of heparin therapy

ArmMeasureGroupValue (NUMBER)
aPTT NomogramNomogram FeasibilitySurveys Completed136 Surveys
aPTT NomogramNomogram FeasibilityAffirmative Responses136 Surveys
Anti-factor Xa NomogramNomogram FeasibilitySurveys Completed112 Surveys
Anti-factor Xa NomogramNomogram FeasibilityAffirmative Responses111 Surveys
p-value: 0.45Fisher Exact
Primary

Nomogram Feasibility

Questionnaires evaluating pragmatic application of nomograms. Question 2: Overall, I am satisfied with the utilization and implementation of the heparin monitoring nomogram.

Time frame: 14 days of heparin therapy

Population: Collected Survey responses from bedside nurses. All surveys were collected as intended.

ArmMeasureGroupValue (NUMBER)
aPTT NomogramNomogram FeasibilitySurveys Completed136 Surveys
aPTT NomogramNomogram FeasibilityAffirmative Responses136 Surveys
Anti-factor Xa NomogramNomogram FeasibilitySurveys Completed112 Surveys
Anti-factor Xa NomogramNomogram FeasibilityAffirmative Responses112 Surveys
p-value: 1Fisher Exact
Primary

Nomogram Feasibility

Questionnaires evaluating pragmatic application of nomograms. Question 3: Overall, I feel that this dosing nomogram is feasible.

Time frame: 14 days of heparin therapy

Population: Collected Survey responses from bedside nurses. All surveys were collected as intended.

ArmMeasureGroupValue (NUMBER)
aPTT NomogramNomogram FeasibilitySurveys Completed136 Surveys
aPTT NomogramNomogram FeasibilityAffirmative Responses135 Surveys
Anti-factor Xa NomogramNomogram FeasibilitySurveys Completed112 Surveys
Anti-factor Xa NomogramNomogram FeasibilityAffirmative Responses112 Surveys
p-value: 1Fisher Exact
Primary

Success of Nomogram

Amount of time sustained in therapeutic anticoagulation range

Time frame: 14 days of heparin therapy

Population: Each group received heparin anticoagulation and had heparin administration guided by a nomogram based on one of two different laboratory assays, aPTT or anti-Xa.

ArmMeasureValue (MEDIAN)
aPTT NomogramSuccess of Nomogram39.8 % of time patients test was therapeutic
Anti-factor Xa NomogramSuccess of Nomogram55.8 % of time patients test was therapeutic
Secondary

Dosing Changes

Number of dosing changes during heparin therapy until first therapeutic

Time frame: 14 days of heparin therapy

ArmMeasureValue (MEDIAN)
aPTT NomogramDosing Changes4.0 dosing changes
Anti-factor Xa NomogramDosing Changes3.0 dosing changes
Secondary

Nomogram Concordance

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

Time frame: 14 days of heparin therapy

Population: paired aPTT samples compared with antiXa samples

ArmMeasureCategoryValue (COUNT_OF_UNITS)
aPTT NomogramNomogram Concordancesubtherapeutic242 tests
aPTT NomogramNomogram Concordancetherapeutic138 tests
aPTT NomogramNomogram Concordancesupratherapeutic36 tests
Anti-factor Xa NomogramNomogram Concordancesubtherapeutic166 tests
Anti-factor Xa NomogramNomogram Concordancetherapeutic223 tests
Anti-factor Xa NomogramNomogram Concordancesupratherapeutic27 tests
Secondary

Time to Therapeutic Dose

Amount of time needed to achieve therapeutic dose from heparin initiation

Time frame: 14 days of heparin therapy

ArmMeasureValue (MEDIAN)
aPTT NomogramTime to Therapeutic Dose48.0 hours
Anti-factor Xa NomogramTime to Therapeutic Dose33.0 hours

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026