A Phase 3 interventional study of Warfarin in Bleeding Post-mechanical Valve Replacement and Thromboembolism Post-mechanical Valve Replacement, sponsored by Population Health Research Institute. Recruiting at 45 sites in 18 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-17.
Sponsored by Population Health Research Institute · Phase 3, Interventional, and Treatment
This study evaluates the use of a lower INR target (1.5 to 2.5) in patients with a mechanical bileaflet heart valve in the aortic position. This study will inform physicians about whether a lower INR target will decrease the risk of bleeding or increase the risk of blood clot formation and stroke. These results have the potential to reduce the burden of bleeding in patients with a mechanical heart valve who require lifelong warfarin (Coumadin) treatment.
Warfarin (Coumadin) is a blood thinner used to prevent blood clot formation in patients with mechanical heart valves. Blood clots can block blood flow to the brain, heart, or other parts of the body. Mechanical heart valves increases the risk of clot so patients with a mechanical heart valve must take warfarin to reduce their risk of stroke and other blood clot-related problems.
The degree to which warfarin 'works' varies from person to person, and so dosage is determined by measuring each person's response to the drug as an 'international normalized ratio' or INR. A patient with an INR over 1.0 has blood that takes longer to clot than average, and increasing INR values represent increasing time required for blood to clot. While an INR over 1.0 decreases clotting risk, it also increases bleeding risk. It is important to carefully balance these risks.
Specific INR targets have been recommended for patients with a mechanical heart valve, but these recommendations differ between scientific groups and are based on low quality evidence. Recent studies suggest that a lower INR target range than is currently recommended can be used safely. A laboratory study showed that warfarin effectively prevents blood clot formation on mechanical heart valves as long as the INR is 1.5 or above. Two moderately-sized clinical studies showed that an INR target range of 1.5-2.5 resulted in less bleeding than the usual higher target range without increasing blood clot formation or stroke in patients with a newer valve model. Whether we could use a lower INR target range for patients with a mechanical aortic valve remains controversial.
This study evaluates the use of a lower INR target (1.5 to 2.5) in patients with a mechanical bileaflet heart valve in the aortic position. This study will inform physicians about whether a lower INR target will decrease the risk of bleeding or increase the risk of blood clot formation and stroke. These results have the potential to reduce the burden of bleeding in patients with a mechanical heart valve who require lifelong warfarin (Coumadin) treatment.
1,383 studies on the registry are indexed under Hemorrhage; 244 are open to participants now.
This study's planned enrollment of 2,625 is above the median of 102 across 926 interventional studies indexed under Hemorrhage.
Browse Hemorrhage studies →Population Health Research Institute is the lead sponsor of 115 studies on the registry; 26 are open to participants now.
Of its 5 completed or terminated interventional studies of FDA-regulated products, 1 (20%) have results posted.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
INR, PT and aPTT (clotting tests)
Blood tests of how long blood takes to clot. The INR is the prothrombin time (PT) put on a common scale; about 1 is usual for someone not taking a blood thinner.
Criteria often make an exception for people on a blood thinner such as warfarin, whose INR is raised on purpose.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Warfarin therapy will be titrated to a target INR in the range of 1.5 to 2.5.
Drug: Warfarin
Warfarin therapy will be titrated to a "standard of care" target INR range.
Drug: Warfarin
Participants in both arms will be on warfarin therapy post-mechanical valve replacement as is standard, but will have different INR target ranges.
Also known as: Coumadin
Thrombosis/thromboembolism
Number of patients who have at least one of the following: ischemic stroke, systemic thromboembolism, and valve thrombosis
Time frame: Through study completion, an expected mean of 2-3 years
Major bleeding
Number of patients that have bleeding that results in the following: 1. Death and/or, 2. Symptomatic bleeding in critical area or organ (e.g. intracranial, intraspinal, intraocular, retroperitoneal, intraarticular, pericardial, in a non-operated joint, or intramuscular with compartment syndrome) and/or, 3. Bleeding that causes drop of hemoglobin level by 20 g/L or more, or that requires the transfusion of 2 or more units of packed red blood cells or whole blood
Time frame: Through study completion, an expected mean of 2-3 years
All cause mortality
Selected rather than cardiovascular mortality, as cause-specific mortality is often difficult to ascertain or define in complex cardiovascular patients in whom multi-end-organ dysfunction may accompany cardiovascular decline.
Time frame: Through study completion, an expected mean of 2-3 years
All clinically important bleeding
Number of patients that experience all clinically important bleeding (major and minor)
Time frame: Through study completion, an expected mean of 2-3 years
Minor bleeding
Number of patients that experience a bleed that does not meet major bleeding criteria
Time frame: Through study completion, an expected mean of 2-3 years
All stroke
Number of patients that experience a strokes, including ischemic stroke, ischemic with secondary transformation, stroke of uncertain classification and hemorrhagic stroke
Time frame: Through study completion, an expected mean of 2-3 years
Ischemic stroke
Number of patients that experience an ischemic stroke, defined as focal brain infarction caused by an arterial (or rarely venous) obstruction and as documented by CT/MRI that is normal or shows an infarct in the clinicall expected area
Time frame: Through study completion, an expected mean of 2-3 years
Hemorrhagic stroke
Number of patients that experience a hemorrhagic stroke, defined as requiring neuroimaging or autopsy confirmation, and includes two subcategories: primary intracerebral hemorrhage and primary subarachnoid hemorrhage
Time frame: Through study completion, an expected mean of 2-3 years
Type 1, 2 or 3 myocardial infarction
Number of patients who experience a type 1, 2 or 3 myocardial infarction
Time frame: Through study completion, an expected mean of 2-3 years
Systemic thromboembolism
Number of patients who experience a systemic thromboembolism
Time frame: Through study completion, an expected mean of 2-3 years
Valve thrombosis
Number of patients who experience a valve thrombosis
Time frame: Through study completion, an expected mean of 2-3 years
Pulmonary embolism
Number of patients who experience a pulmonary embolism
Time frame: Through study completion, an expected mean of 2-3 years
Deep vein thrombosis
Number of patients who experience a deep vein thrombosis
Time frame: Through study completion, an expected mean of 2-3 years
New renal replacement therapy
Number of patients requiring new renal replacement therapy
Time frame: Through study completion, an expected mean of 2-3 years
Time in therapeutic range
The percentage of time the patient's INR was within the target range
Time frame: Through study completion, an expected mean of 2-3 years
Proportion of patients with extreme INR values (>4)
The proportion of patients with at least one reported INR value above 4
Time frame: Through study completion, an expected mean of 2-3 years
Plan to share: No — We will establish a plan for the full-scale study but there is no plan to make IPD available to other researchers.
Started Sep 2019 (actual). Primary completion is estimated for Dec 2028, 111 months after the start.
Of 45 non-industry phase 3 interventional studies under Hemorrhage, half reached primary completion within 42 months of starting (the median), counting those still running; a quarter within 26 and three quarters within 72. This study's planned 111 months is above that.
Counting every sponsor, half of 71 studies reached it within 42 months; a quarter within 26 and three quarters within 65.
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Studies of the drug tested here: Warfarin
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