AuthorisedTherapeutic confirmatory (Phase III)Interventional

Evaluation of an asPirin-free strategy with ticAgrelor in patieNTs witH a myocardial infarction treatEd medically alONe (PANTHEON)

After having a heart attack, most people are prescribed blood-thinning tablets to prevent future blood clots. Usually, doctors recommend taking two different blood thinners together, such as aspirin and ticagrelor. However, taking both medicines can raise your risk of bleeding. This trial, called PANTHEON, is testing whether people who have had a heart attack and did not need surgery or stents can safely take ticagrelor on its own. Half the participants will take ticagrelor with aspirin, while the other half will take ticagrelor alongside a dummy pill (placebo) instead of aspirin. Researchers will carefully compare both groups to find out if skipping aspirin lowers bleeding problems while still giving the same strong protection against further heart attacks or strokes. The results will help doctors choose the safest treatment plan for future heart patients.

At a glance

Status

Authorised

Phase

Therapeutic confirmatory (Phase III)

Sponsor

Montreal Heart Institute

Enrolment target

600

Start

18 Aug 2026

myocardial infarction

What is this study about?

When someone has a heart attack, it is usually caused by a blood clot blocking blood flow to the heart muscle. To stop this from happening again, doctors commonly prescribe medicines known as blood thinners or antiplatelet drugs. For many years, the standard approach has been to take two different blood thinners together—typically aspirin alongside another medicine such as ticagrelor.

While taking two blood thinners offers good protection against new clots, it also makes it harder for your blood to clot when you need it to, such as if you get a cut or nosebleed. This means the risk of unusual or serious bleeding is higher. In some cases, heart attack patients are treated with medicines alone, without having procedures like a stent or bypass surgery. Doctors want to know if these patients truly need both blood thinners, or if taking just one is enough.

The PANTHEON study is designed to answer this question. Researchers want to see whether using ticagrelor by itself works just as well to prevent heart attacks, strokes, and blood clots as the combined treatment, while causing fewer bleeding problems. By taking aspirin out of the equation, the hope is to find a gentler, safer option that still keeps the heart well protected.

Finding the right balance between preventing clots and avoiding bleeding is vital for long-term health. If this trial shows that ticagrelor alone is effective and causes less bleeding, it could change standard guidelines in the UK and worldwide, helping future heart patients receive a safer, tailored treatment.

Key takeaways

The trial compares taking ticagrelor alone against taking ticagrelor together with aspirin.
It is for adults who have had a heart attack treated with medicine alone, without stents or surgery.
The aim is to reduce the risk of bleeding while keeping the heart safe from future clots.
Participation is voluntary, and all patients receive active blood-thinning medicine.

Who may be eligible?

This trial is for adults aged 18 and older who have recently had a heart attack. It is open to both men and women.

It specifically focuses on patients whose heart attack is being managed using medications alone, meaning they have not had surgery or a stent fitted to open up their heart arteries during their current care.

Because this is a trial using blood-thinning medicines, people who currently have a high risk of severe bleeding or who cannot safely take ticagrelor or aspirin will not be able to join. The hospital study team will check your full medical history and current medications to confirm if you are suitable.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you 18 years of age or older?
Have you recently had a heart attack?
Is your heart condition being managed with medicines alone (without a stent or surgery)?
Are you able to take daily blood-thinning tablets?
Are you free from any condition that causes a very high risk of bleeding?

Answer every question to see your result.

What does participation involve?

If you take part, you will be placed into one of two groups by chance (randomly). Everyone in the study will take ticagrelor. One group will also take aspirin, while the other group will take a dummy pill (placebo) that looks identical to aspirin. Neither you nor your doctor will know which group you are in, ensuring the test is fair.

You will take your study tablets daily as instructed. Throughout the trial, you will attend regular check-ups at your local hospital clinic or have telephone appointments so the research team can monitor your health. During these check-ups, the team may perform routine physical checks, take blood tests, and ask you about any side effects or signs of unusual bleeding.

You will be followed up over several months to track your progress. The research team will explain the exact number of clinic visits and how long you will need to take the study tablets before you decide to take part.

Potential risks and benefits

The main benefit of taking part is that your heart health will be closely watched by specialist heart teams, and you will help find safer treatments for other patients in the future. The main risk with blood-thinning medicines is an increased chance of bleeding, which can range from minor issues like easy bruising and nosebleeds to rarer, more serious bleeding. There is also a small risk that taking one medicine might not offer the exact same protection as two, which is what the trial is testing. Taking part is completely voluntary, and you can withdraw from the study at any time without your regular NHS medical care being affected.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

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Unverified
France

Common questions

What is the PANTHEON study trying to find out?

It is testing whether taking one blood thinner (ticagrelor) alone causes less bleeding than taking it with aspirin, while still protecting you from another heart attack.

What is a placebo?

A placebo is a dummy pill that looks just like the real medicine but contains no active ingredients. It helps doctors see the true effects of the real drug.

Will I definitely receive treatment for my heart?

Yes. Every participant in this study will receive the active heart medication ticagrelor, along with standard medical care.

What should I do if I notice bleeding during the trial?

You should contact the study team or your doctor immediately. They will give you clear contact numbers to call 24 hours a day if you have any worries.

Can I leave the study if I change my mind?

Yes. You are free to stop taking part at any point, and your normal healthcare will continue as usual.