ACS - Acute Coronary SyndromePhase 4FLORA-ACSNCT07203846
Modulation of Gut MicroFLORA With Rifaximin to Reduce High Platelet Reactivity in Post-ACS Patients on Ticagrelor
A Phase 4 study testing Rifaximin in people with ACS - Acute Coronary Syndrome and Ticagrelor, run by Collegium Medicum w Bydgoszczy at 1 site in Poland.
Trial summary
The FLORA-ACS study aims to evaluate the relationship between dysbiosis and high platelet reactivity during treatment with ticagrelor in patients with a history of acute coronary syndromes and investigate the use of rifaximin to eliminate dysbiosis and thus provide effective antiplatelet treatment. Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- ACS - Acute Coronary Syndrome, Ticagrelor, Microbiota
- What is being tested?
- Rifaximin
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 50 participants
- Where
- 1 sitePoland
- Study dates
- 1 Jan 2026to 30 Jun 2027
- Phase
- Phase 4
- 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 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Between 18 and 80 years of age
- History of acute coronary syndrome no sooner than 1 month and no later than 12 months prior to study inclusion
- Current treatment with ticagrelor (90 mg orally twice a day)
- High platelet reactivity assessed with multiple electrode aggregometry method (AUC of >46 U)
- Provision of informed consent prior to any study procedures
Who cannot join
- History of hypersensitivity to rifaximin or other rifamycin-derived agent
- Ongoing treatment with rifamycins
- Platelet count < 100×10^9/L or > 450×10^9/L
- Treatment with antibiotics, probiotics, or glucocorticoids within 3 months prior to study inclusion
- History of gastrointestinal diseases such as inflammatory bowel disease, bowel obstruction, or gastrointestinal tumor
- Infection, including gastrointestinal infection, within a month prior to study inclusion
Show all 12Show fewer
- History of Clostridium difficile infection
- Current use of specific medications (warfarin, glycoprotein IIb/IIIa inhibitors, immunosuppressants, bile acid sequestrants, antidiarrheal agents)
- Impaired liver function classified as Child-Pugh class B or C
- Hemodynamic instability
- Pregnancy or breastfeeding
- Patients considered by the investigator to be uncooperative
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Poland1 site
Cardiology Department, Dr. A. Jurasz University Hospital
Bydgoszcz, Cuiavian-Pomeranian, 85-094
About this study
Official title: Modulation of Gut Microflora With Rifaximin to Reduce High Platelet Reactivity in Post-Acute Coronary Syndrome Patients on Ticagrelor (FLORA-ACS)
The FLORA-ACS study aims to evaluate the relationship between dysbiosis and high platelet reactivity during treatment with ticagrelor in patients with a history of acute coronary syndromes and investigate the use of rifaximin to eliminate dysbiosis and thus provide effective antiplatelet treatment.
Read the detailed description
A research hypothesis has been formulated indicating dysbiosis of the gut microbiota as a possible cause of high platelet reactivity (HPR) during treatment with an antiplatelet agent, ticagrelor, in post-acute coronary syndrome (ACS) patients. The use of rifaximin, an antibiotic exhibiting an eubiotic effect, may correct gut dysbiosis and help determine whether changes in the microbiota influence HPR.
The FLORA-ACS study will enroll 50 subjects with a history of ACS treated with ticagrelor (standard maintenance dose of 90 mg orally twice a day) and characterized by HPR. Participants will be enrolled in the study no sooner than 1 month and no later than 12 months following the ACS incident.
Platelet activity will be tested using the multiple electrode aggregometry method (Multiplate analyzer) with the HPR defined based on the consensus paper of the Working Group on On-Treatment Platelet Reactivity. Concurrently, fecal samples will be collected for microbiome profiling. The microbiota will be analyzed in terms of fecal bacterial richness and diversity using 16S ribosomal RNA sequencing.
Participants will receive a 7-day course of oral rifaximin (400 mg every 12 hours). Both platelet activity and microbiota testing will be conducted at baseline and post-treatment. Additional laboratory testing will include complete blood count and C-reactive protein. An analysis of major adverse cardiovascular events (MACE) occurrence within a 6-month follow-up period is planned.
- Conditions
- ACS - Acute Coronary Syndrome, Ticagrelor, Microbiota, Platelet Aggregation, Myocardial Infarction (MI), Blood Platelets
- Being tested
- Rifaximin
- Keywords
- high platelet reactivity, HPR, Multiplate aggregometry, multiple electrode aggregometry, MEA, microbiome, gut flora, eubiotic, 16S rRNA sequencing, P2Y12 inhibitor
- Medical subject headings
- Acute Coronary Syndrome, Myocardial Infarction, Dysbiosis
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RifaximinDrug
Also called Xifaxan
Participants receiving a 7-day course of oral rifaximin 400 mg every 12 hours
| Study group | Role | What they receive |
|---|---|---|
| High platelet reactivity patients receiving rifaximin | Experimental | Participants identified as having high platelet reactivity treated with oral rifaximine Receives: Drug: Rifaximin |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in platelet reactivity in Multiplate
Relative reduction in platelet reactivity from baseline to post-intervention by >10%, assessed with Multiplate analyzer (multiple electrode aggregometry)
Measured: 0-7 days
Achievement of platelet reactivity below HPR
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with Multiplate analyzer (multiple electrode aggregometry)
Measured: 0-7 days
Secondary outcomes (5)
Relative reduction in platelet reactivity
Relative reduction in platelet reactivity from baseline to post-intervention by >10%, assessed with VerifyNow P2Y12 assay
Measured: 0-7 days
Achieving platelet reactivity below HPR in VerifyNow
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with VerifyNow P2Y12 assay
Measured: 0-7 days
Relative reduction in platelet reactivity in thromboelastography
Relative reduction in platelet reactivity from baseline to post-intervention by >10%, assessed with Platelet Mapping assay (thromboelastography)
Measured: 0-7 days
Achieving platelet reactivity below HPR in thromboelastography
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with Platelet Mapping assay (thrombelastography)
Measured: 0-7 days
Changes in microbiome profile
Changes in microbiome profile post-intervention assessed using 16S rRNA sequencing
Measured: 0-7 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Oct 2025
- Study start1 Jan 2026 (estimated)
- Primary completion31 Dec 2026 (estimated)
- Study completion30 Jun 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ACS - Acute Coronary SyndromeStudies of the same condition, open and under way.
- 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
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Collegium Medicum w Bydgoszczy
- Sponsor type
- University, hospital or other
- Collaborators
- Ministry of Science and Higher Education, Poland
- Responsible party
- Principal investigator, Jacek Kubica, Collegium Medicum w Bydgoszczy
- Investigators
- Jacek Kubica, Prof., Principal investigator, Collegium Medicum w Bydgoszczy
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07203846
- Sponsor's protocol ID
- FLORA-ACS
- Acronym
- FLORA-ACS
- Status last verified
- Sep 2025
- First submitted
- 25 Sep 2025
- Last updated
- 2 Oct 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 2 Oct 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Modulation of Gut Microflora With Rifaximin to Reduce High Platelet Reactivity in Post-Acute Coronary Syndrome Patients on Ticagrelor (FLORA-ACS)
- ClinicalTrials.gov ID
- NCT07203846
- Acronym / sponsor ID
- FLORA-ACS / FLORA-ACS
- Conditions
- ACS - Acute Coronary Syndrome, Ticagrelor, Microbiota, Platelet Aggregation, Myocardial Infarction (MI), Blood Platelets
- Keywords
- high platelet reactivity, HPR, Multiplate aggregometry, multiple electrode aggregometry, MEA, microbiome, gut flora, eubiotic
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- Collegium Medicum w BydgoszczyUniversity, hospital or other
- Collaborators
- Ministry of Science and Higher Education, Poland
- Study start
- 1 Jan 2026 (estimated)
- Primary completion
- 31 Dec 2026 (estimated)
- Study completion
- 30 Jun 2027 (estimated)
- First posted
- 2 Oct 2025 (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 FLORA-ACS study aims to evaluate the relationship between dysbiosis and high platelet reactivity during treatment with ticagrelor in patients with a history of acute coronary syndromes and investigate the use of rifaximin to eliminate dysbiosis and thus provide effective antiplatelet treatment.
Detailed description
A research hypothesis has been formulated indicating dysbiosis of the gut microbiota as a possible cause of high platelet reactivity (HPR) during treatment with an antiplatelet agent, ticagrelor, in post-acute coronary syndrome (ACS) patients. The use of rifaximin, an antibiotic exhibiting an eubiotic effect, may correct gut dysbiosis and help determine whether changes in the microbiota influence HPR.
The FLORA-ACS study will enroll 50 subjects with a history of ACS treated with ticagrelor (standard maintenance dose of 90 mg orally twice a day) and characterized by HPR. Participants will be enrolled in the study no sooner than 1 month and no later than 12 months following the ACS incident.
Platelet activity will be tested using the multiple electrode aggregometry method (Multiplate analyzer) with the HPR defined based on the consensus paper of the Working Group on On-Treatment Platelet Reactivity. Concurrently, fecal samples will be collected for microbiome profiling. The microbiota will be analyzed in terms of fecal bacterial richness and diversity using 16S ribosomal RNA sequencing.
Participants will receive a 7-day course of oral rifaximin (400 mg every 12 hours). Both platelet activity and microbiota testing will be conducted at baseline and post-treatment. Additional laboratory testing will include complete blood count and C-reactive protein. An analysis of major adverse cardiovascular events (MACE) occurrence within a 6-month follow-up period is planned.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| High platelet reactivity patients receiving rifaximin | Experimental | Drug: RifaximinParticipants identified as having high platelet reactivity treated with oral rifaximine |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Between 18 and 80 years of age
- History of acute coronary syndrome no sooner than 1 month and no later than 12 months prior to study inclusion
- Current treatment with ticagrelor (90 mg orally twice a day)
- High platelet reactivity assessed with multiple electrode aggregometry method (AUC of >46 U)
- Provision of informed consent prior to any study procedures
Key exclusion criteria (12 listed)
- History of hypersensitivity to rifaximin or other rifamycin-derived agent
- Ongoing treatment with rifamycins
- Platelet count < 100×10^9/L or > 450×10^9/L
- Treatment with antibiotics, probiotics, or glucocorticoids within 3 months prior to study inclusion
- History of gastrointestinal diseases such as inflammatory bowel disease, bowel obstruction, or gastrointestinal tumor
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 |
|---|---|---|
| RifaximinAlso: XifaxanParticipants receiving a 7-day course of oral rifaximin 400 mg every 12 hours | Drug | High platelet reactivity patients receiving rifaximin |
Primary outcome
Change in platelet reactivity in Multiplate
Time frame: 0-7 days
Relative reduction in platelet reactivity from baseline to post-intervention by >10%, assessed with Multiplate analyzer (multiple electrode aggregometry)
Achievement of platelet reactivity below HPR
Time frame: 0-7 days
Achieving platelet reactivity below HPR in a patient with a higher baseline value, assessed with Multiplate analyzer (multiple electrode aggregometry)
5 secondary outcomes
Relative reduction in platelet reactivity
Time frame: 0-7 days
Achieving platelet reactivity below HPR in VerifyNow
Time frame: 0-7 days
Relative reduction in platelet reactivity in thromboelastography
Time frame: 0-7 days
Achieving platelet reactivity below HPR in thromboelastography
Time frame: 0-7 days
Changes in microbiome profile
Time frame: 0-7 days
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 2 Oct 2025.
- Individual participant dataSharing planned: No
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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.
Jacek Kubica, Prof. principal investigator
Collegium Medicum w Bydgoszczy
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Rifaximin in people with ACS - Acute Coronary Syndrome and Ticagrelor, run by Collegium Medicum w Bydgoszczy at 1 site in Poland.
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 5 inclusion and 12 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: opening soon, as of the sponsor's last update on 2 Oct 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Poland. 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.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
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 Klaudyna Grzelakowska, MD (+48525854023, klaudyna.grzelakowska@gmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in platelet reactivity in Multiplate (time frame: 0-7 days). 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 2 Oct 2025.