Antiphospholipid SyndromeNCT05646394
Registry on Augmented Antithrombotic Treatment Regimens for Patients With Arterial Thrombotic APS
An observational study of Antiphospholipid Syndrome and Arterial Thrombosis, run by McMaster University at 3 sites in 2 countries.
Trial summary
The goal of this registry is to gather more information on the efficacy and safety of various antithrombotic regimens. The registry collects data on patients with antiphospholipid syndrome and an arterial event within the past 12 months, on treatment with either A) a VKA with therapeutic range, INR 2.0-3.0 plus… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Antiphospholipid Syndrome, Arterial Thrombosis
- What is being tested?
- Dual antiplatelet therapy, Combined antithrombotic therapy and Vitamin K antagonist standard intensity
- How many people
- 150 participants
- Where
- 3 sitesin 2 countries
- Study dates
- 1 Jul 2022to 31 Dec 2029
- How long will I take part?
- 2 Years
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: The decision on the treatment regimen should have been made by the treating physician on clinical grounds and judgement, prior to informing the patients about the registry. The information should include that vitamin K antagonist is the recommended standard, either alone or in combination and, in case dual antiplatelet regimen is chosen, an explanation to the patient for what reasons it should be used or continued. Patients that have been started on either of the eligible regimens after the most recent arterial thromboembolic event and within the past 12 months can be approached and informed about the study. If the patient meets the inclusion criteria and does not have any of the exclusion criteria, the investigator or designated representative obtains consent for collection of data.
Who may be able to join
- Patients of at least 18 years of age with confirmed antiphospholipid syndrome according to Sydney criteria and with first or recurrent arterial thrombotic manifestation, including those with asymptomatic brain infarcts on diagnostic imaging.
- Treatment with either A) a vitamin K antagonist (VKA) with therapeutic range, international normalized ratio (INR) 2.0-3.0 plus low-dose aspirin (75-100 mg daily), B) a VKA alone with therapeutic range, INR 2.0-3.0 or C) VKA with therapeutic range, INR 3.0-4.0, or D) with a dual antiplatelet regimen, if considered appropriate by the treating physician.
- Signed informed consent obtained (in jurisdictions where required).
Who cannot join
- Inability to follow the patient due to geographical or other reasons.
- Patients with documented poor compliance.
- Bleeding risk that in the opinion of the treating physician makes combination antithrombotic therapy unsafe.
- Pregnancy or planned pregnancy.
- Venous thrombotic event diagnosed after the last arterial event.
Trial locations and contacts
3 sites in 2 countries. Contact the study team or a site near you to ask about taking part.
3 sites in 2 countries
Argentina2 sites, 2 recruiting
- Recruiting
Instituto de Investigaciones en Salud Pública, Universidad de Buenos Aires
Buenos Aires, Buenos Aires F.D., C1113 AAJ
Patricia Casais, MD, PhD, (11)50324141, patricia.casais@odontologia.uba.ar
- Recruiting
Clinica Universitaria Reina Fabiola
Córdoba
Soledad Molnar, MD, 0351-4142121
Canada1 site, 1 recruiting
- Recruiting
McMaster University
Hamilton, Ontario, L9H 7M1
Sam Schulman, 9059796437, schulms@mcmaster.ca
About this study
The goal of this registry is to gather more information on the efficacy and safety of various antithrombotic regimens. The registry collects data on patients with antiphospholipid syndrome and an arterial event within the past 12 months, on treatment with either A) a VKA with therapeutic range, INR 2.0-3.0 plus low-dose aspirin (75-100 mg daily), B) a VKA alone with therapeutic range, INR 2.0-3.0, C) a VKA with therapeutic range, INR 3.0-4.0, or D) with a dual antiplatelet regimen. The follow-up is 2 years.
Read the detailed description
The optimal antithrombotic management of patients with antiphospholipid syndrome and arterial thrombotic events is unclear. The guidelines provide several options, mostly with vitamin K antagonist with/without an antiplatelet agent. Dual antiplatelet therapy (DAPT) was in a meta-analysis potentially effective, but included studies were few and small.
The primary aim is to compare a vitamin K antagonist (VKA), i.e. warfarin, acenocoumarol, phenprocoumon etc, with international normalized ratio 2.0-3.0 plus low-dose aspirin (75-100 mg) with DAPT - typically low-dose aspirin plus clopidogrel (75 mg daily) but other combinations will be acceptable. The registry will also include patients treated with VKA alone at standard- or high-intensity, since this is recommended and will serve as reference groups in comparison with VKA + low-dose aspirin and versus DAPT. The outcomes are (efficacy) arterial or venous thromboembolism, vascular death or (safety) major bleeding.
A secondary objective is to analyze how the cardiovascular risk factors (hypertension, hyperlipidemia, obesity, smoking, diabetes, and heart failure), venous thrombotic risk factors (previous venous thromboembolism, cancer, immobility, chronic inflammatory disease) and anti-phospholipid profile contribute to recurrent arterial thrombosis.
- Conditions
- Antiphospholipid Syndrome, Arterial Thrombosis
- Being tested
- Dual antiplatelet therapy, Combined antithrombotic therapy, Vitamin K antagonist standard intensity, Vitamin K antagonist high intensity
- Keywords
- anticoagulation, vitamin K antagonist, antiaggregant, stroke, myocardial infarction, hemorrhage
- Medical subject headings
- Antiphospholipid Syndrome, Stroke, Myocardial Infarction, Hemorrhage
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dual antiplatelet therapyDrug
Also called Aspirin, Plavix, Brilinta, Effient
Aspirin plus any of clopidogrel, ticagrelor or prasugrel
Combined antithrombotic therapyDrug
Also called Vitamin K antagonist plus aspirin, Vitamin K antagonist plus antiaggregant, Vitamin K antagonist plus antiplatelet agent
Combination of a vitamin K antagonist, such as warfarin, acenocoumarol, phenprocoumon, phenindione etc, with low-dose aspirin.
Vitamin K antagonist standard intensityDrug
Also called VKA
vitamin K antagonist, such as warfarin, acenocoumarol, phenprocoumon, phenindione etc, with therapeutic range, international normalized ratio 2.0-3.0
Vitamin K antagonist high intensityDrug
Also called VKA
vitamin K antagonist, such as warfarin, acenocoumarol, phenprocoumon, phenindione etc, with therapeutic range, international normalized ratio 3.0-4.0
What is being measured
The primary outcome is the main question the study is designed to answer.
Number of Participants with thromboembolism verified by diagnostic imaging, electrocardiogram or troponin rise
Composite of arterial thrombosis (stroke, myocardial infarction, peripheral arterial thrombosis or embolism), venous thromboembolism (thrombosis in any deep vein or pulmonary embolism), and vascular death.
Measured: 2 years
Number of Participants with major hemorrhage fulfilling at least one of the International Society on Thrombosis and Haemostasis criteria
Major hemorrhage according to the International Society on Thrombosis and Haemostasis
Measured: 2 years
Secondary outcomes (3)
Number of Participants with arterial thrombosis verified by diagnostic imaging
stroke, myocardial infarction, peripheral arterial thrombosis or embolism
Measured: 2 years
Number of Participants with venous thromboembolism verified by diagnostic imaging
thrombosis in any deep vein or pulmonary embolism
Measured: 2 years
Number of Participants with vascular death verified by diagnostic imaging, electrocardiogram or troponin rise
Death due to arterial or venous thromboembolism
Measured: 2 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Dec 2022
- Study start1 Jul 2022
- Primary completion31 Jul 2029 (estimated)
- Study completion31 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Antiphospholipid SyndromeStudies of the same condition, open and under way.
- More trials run by McMaster UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 150 participants (estimated)
- Target duration
- 2 Years
Sponsor and investigators
- Lead sponsor
- McMaster University
- Sponsor type
- University, hospital or other
- Collaborators
- International Society on Thrombosis and Haemostasis
- Responsible party
- Sponsor
- Investigators
- Cary Clark, Study director, International Society on Thrombosis and Haemostasis
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05646394
- Sponsor's protocol ID
- AATAAPS2021
- Status last verified
- Nov 2025
- First submitted
- 5 Dec 2022
- Last updated
- 9 Dec 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: The study protocol and ICF are available on the ISTH website (under SSC - RedCap. IPD will be shared after the primary publication.
Study at a glance
From the registry record, last updated by the sponsor on 9 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Registry on Augmented Antithrombotic Treatment Regimens for Patients With Arterial Thrombotic APS
- ClinicalTrials.gov ID
- NCT05646394
- Acronym / sponsor ID
- AATAAPS2021
- Conditions
- Antiphospholipid Syndrome, Arterial Thrombosis
- Keywords
- anticoagulation, vitamin K antagonist, antiaggregant, stroke, myocardial infarction, hemorrhage
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 150 participants (estimated)
- Lead sponsor
- McMaster UniversityUniversity, hospital or other
- Collaborators
- International Society on Thrombosis and Haemostasis
- Study start
- 1 Jul 2022 (actual)
- Primary completion
- 31 Jul 2029 (estimated)
- Study completion
- 31 Dec 2029 (estimated)
- First posted
- 12 Dec 2022 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this registry is to gather more information on the efficacy and safety of various antithrombotic regimens. The registry collects data on patients with antiphospholipid syndrome and an arterial event within the past 12 months, on treatment with either A) a VKA with therapeutic range, INR 2.0-3.0 plus low-dose aspirin (75-100 mg daily), B) a VKA alone with therapeutic range, INR 2.0-3.0, C) a VKA with therapeutic range, INR 3.0-4.0, or D) with a dual antiplatelet regimen. The follow-up is 2 years.
Detailed description
The optimal antithrombotic management of patients with antiphospholipid syndrome and arterial thrombotic events is unclear. The guidelines provide several options, mostly with vitamin K antagonist with/without an antiplatelet agent. Dual antiplatelet therapy (DAPT) was in a meta-analysis potentially effective, but included studies were few and small.
The primary aim is to compare a vitamin K antagonist (VKA), i.e. warfarin, acenocoumarol, phenprocoumon etc, with international normalized ratio 2.0-3.0 plus low-dose aspirin (75-100 mg) with DAPT - typically low-dose aspirin plus clopidogrel (75 mg daily) but other combinations will be acceptable. The registry will also include patients treated with VKA alone at standard- or high-intensity, since this is recommended and will serve as reference groups in comparison with VKA + low-dose aspirin and versus DAPT. The outcomes are (efficacy) arterial or venous thromboembolism, vascular death or (safety) major bleeding.
A secondary objective is to analyze how the cardiovascular risk factors (hypertension, hyperlipidemia, obesity, smoking, diabetes, and heart failure), venous thrombotic risk factors (previous venous thromboembolism, cancer, immobility, chronic inflammatory disease) and anti-phospholipid profile contribute to recurrent arterial thrombosis.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Target follow-up
- 2 Years
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- The decision on the treatment regimen should have been made by the treating physician on clinical grounds and judgement, prior to informing the patients about the registry. The information should include that vitamin K antagonist is the recommended standard, either alone or in combination and, in case dual antiplatelet regimen is chosen, an explanation to the patient for what reasons it should be used or continued. Patients that have been started on either of the eligible regimens after the most recent arterial thromboembolic event and within the past 12 months can be approached and informed about the study. If the patient meets the inclusion criteria and does not have any of the exclusion criteria, the investigator or designated representative obtains consent for collection of data.
Key inclusion criteria (3 listed)
- Patients of at least 18 years of age with confirmed antiphospholipid syndrome according to Sydney criteria and with first or recurrent arterial thrombotic manifestation, including those with asymptomatic brain infarcts on diagnostic imaging.
- Treatment with either A) a vitamin K antagonist (VKA) with therapeutic range, international normalized ratio (INR) 2.0-3.0 plus low-dose aspirin (75-100 mg daily), B) a VKA alone with therapeutic range, INR 2.0-3.0 or C) VKA with therapeutic range, INR 3.0-4.0, or D) with a dual antiplatelet regimen, if considered appropriate by the treating physician.
- Signed informed consent obtained (in jurisdictions where required).
Key exclusion criteria (5 listed)
- Inability to follow the patient due to geographical or other reasons.
- Patients with documented poor compliance.
- Bleeding risk that in the opinion of the treating physician makes combination antithrombotic therapy unsafe.
- Pregnancy or planned pregnancy.
- Venous thrombotic event diagnosed after the last arterial event.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Dual antiplatelet therapyAlso: Aspirin, Plavix, Brilinta, EffientAspirin plus any of clopidogrel, ticagrelor or prasugrel | Drug | – |
| Combined antithrombotic therapyAlso: Vitamin K antagonist plus aspirin, Vitamin K antagonist plus antiaggregant, Vitamin K antagonist plus antiplatelet agentCombination of a vitamin K antagonist, such as warfarin, acenocoumarol, phenprocoumon, phenindione etc, with low-dose aspirin. | Drug | – |
| Vitamin K antagonist standard intensityAlso: VKAvitamin K antagonist, such as warfarin, acenocoumarol, phenprocoumon, phenindione etc, with therapeutic range, international normalized ratio 2.0-3.0 | Drug | – |
| Vitamin K antagonist high intensityAlso: VKAvitamin K antagonist, such as warfarin, acenocoumarol, phenprocoumon, phenindione etc, with therapeutic range, international normalized ratio 3.0-4.0 | Drug | – |
Primary outcome
Number of Participants with thromboembolism verified by diagnostic imaging, electrocardiogram or troponin rise
Time frame: 2 years
Composite of arterial thrombosis (stroke, myocardial infarction, peripheral arterial thrombosis or embolism), venous thromboembolism (thrombosis in any deep vein or pulmonary embolism), and vascular death.
Number of Participants with major hemorrhage fulfilling at least one of the International Society on Thrombosis and Haemostasis criteria
Time frame: 2 years
Major hemorrhage according to the International Society on Thrombosis and Haemostasis
3 secondary outcomes
Number of Participants with arterial thrombosis verified by diagnostic imaging
Time frame: 2 years
Number of Participants with venous thromboembolism verified by diagnostic imaging
Time frame: 2 years
Number of Participants with vascular death verified by diagnostic imaging, electrocardiogram or troponin rise
Time frame: 2 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 Dec 2025.
- Case report form - DO NOT ENTER DATA WITHOUT OBTAINING CENTER NUMBER; links to study protocol, ethics approval; informed consent formLink provided by the sponsor.
- Individual participant dataSharing planned: Yes. The study protocol and ICF are available on the ISTH website (under SSC - RedCap. IPD will be shared after the primary publication.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Cary Clark study director
International Society on Thrombosis and Haemostasis
3 sites in 2 countries: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Antiphospholipid Syndrome and Arterial Thrombosis, run by McMaster University at 3 sites in 2 countries.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 9 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Argentina, Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Sam Schulman, MD, PhD (+19055270271 ext. 44810, schulms@mcmaster.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Number of Participants with thromboembolism verified by diagnostic imaging, electrocardiogram or troponin rise (time frame: 2 years). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 Dec 2025.