Millions of patients at high risk of a fatal heart attack could be taking a drug that may not even be effective, top doctors have warned. 

Anti-clotting pill ticagrelor was approved for use on the NHS in 2011 after trials claimed it could prevent one in five deaths after a heart attack.

The twice-daily pill, sold as Brilinta, is given to people with acute coronary syndrome —a sudden reduction of blood to the heart—reducing the risk of deadly clots and strokes.

Since then, studies have questioned if the AstraZeneca drug is as good as its rivals, such as clopidogrel, with some even suggesting it may even increase the risk of bleeding. 

Now, experts have discovered ‘evidence of serious misreporting’ in two clinical trials, pivotal to getting the drug approved in the UK and US, ‘raising doubts over its approval’. 

The BMJ investigation claimed the ‘primary endpoint’ results—the key measure to determine whether a treatment is effective—for both trials were inaccurately reported in leading cardiology journal Circulation. 

It also said around a quarter of the readings from machines used in the trials were not included in the data sets, the US medicine’s regulator, the Food and Drug Administration (FDA) used to approve the drug. 

Dr Victor Serebruany, an expert in cardiovascular pharmacology at Johns Hopkins University in Maryland, who has been critical of the drug for over a decade said: ‘It’s been obvious for years that there is something wrong with the data. 

The twice-daily pill, sold as Brilinta, is given to people with acute coronary syndrome —a sudden reduction of blood to the heart—reducing the risk of deadly clots and strokes

Since then, studies have questioned if the AstraZeneca drug is as good as its rivals, such as clopidogrel, with some even suggesting it may even increase the risk of bleeding

‘That the FDA’s leadership could look past all these problems—on top of the many problems their own reviewers identified and are now being discovered by The BMJ—is unconscionable. 

‘We all need to know how and why that happened.

‘If doctors had known what happened in these trials, they would never have started using ticagrelor.’   

In order for ticagrelor to get approved, clinical trials had to prove that it was a better drug than competitors in a phase 3 trial.

After phase 3 and drug approval, the FDA and MHRA in the UK, continues monitoring it in phase 4 trials, to see if there are any additional problems with the drug.

But the BMJ analysis of two phase 2 trial results found there were instances of patients who’s blood ‘platelet aggregation dramatically increased’.

This is where platelets—a type of blood cell—stick together to form clumps which can lead to blood clots, exactly what the drug aims to prevent. 

It ‘suggests incorrect laboratory readings’, the BMJ said. 

While some warning signs are easy to spot, such as severe chest pain, others are more vague and hard to pinpoint

Assessing the readings from platelet machines used at the two trial sites, led by cardiologist Dr Paul Gurbel, they also found more than 60 of the 282 readings were not included in the datasets submitted to the FDA. 

‘The platelet activity levels not entered were significantly higher than those used in the Circulation papers and FDA datasets,’ they claimed. 

‘It is unclear whose blood was sampled, and why those measurements did not contribute to data in either trial.’ 

A spokesperson for the Sinai Center for Thrombosis Research and Drug Development, which Dr Gurbel leads, said: ‘Any allegations of any research misconduct in the two studies are baseless and erroneous.’ 

In the UK, the drug is prescribed around 45,000 times per month on the NHS.

According to medicines watchdog the National Institute for Health and Care Excellence (NICE), patients are advised to take the drug twice a day at 90mg for around a year after a heart attack. 

A lower dose of 60mg, may then be prescribed by doctors for up to a further three years.  

It may also be taken by those who have suffered a minor stroke or a transient ischaemic attack at 90mg alongside aspirin. 

Stroke symptoms are commonly remembered under this four-letter acronym, FAST. Patients experiencing a stroke can often have their face drop on one side, struggle to lift both arms and have slurred speech, while time is essential, as immediate treatment for a transient ischemic attack (TIA) or minor stroke can substantially slash the risk of a much deadlier major stroke

Other – just as common – tell-tale signs of a looming stroke, often fall under the radar. These include sudden numbness on one side of the body, sudden vertigo and difficulty swallowing

The body naturally forms blood clots in order to patch wounds and stop bleeding.

But over time, things like age, smoking and excessive weight gain can make blood clots more common. 

These kinds of clots also become more common after someone has a heart attack or blood vessel disorder, coronary artery disease.

When someone overproduces these clots they can clog blood vessels, interrupting blood flow or weakening the walls of blood vessels, causing aneurysms and heart attacks. 

Circulation and AstraZeneca did not respond to a request for comment from the BMJ. MailOnline has also approached AstraZeneca for comment.