Antithrombotic Therapy to Ameliorate Complications of COVID-19: The ATTACC Randomized Trial

Research title

Large scale randomised controlled trial to determine if daily treatment of anticoagulant heparin can improve the outcome of hospitalised COVID-19 patients


University Health Network in partnership with the University of Toronto, with funding from LifeArc, is set to conduct a large multicentre randomised control trial with up to 3000 patients. It aims to determine if the anticoagulant heparin, which is already on the market, may improve the outcome of COVID-19 patients. Small observational studies using heparin have shown it to be beneficial in treating COVID-19, however no controlled trials have been carried out on the drug thus far.

It has the potential to be beneficial due to its anti-coagulant properties, as severe infections of COVID-19 have been associated with the formation of blood clots in the lungs and other organs, also known as thrombosis.

Research organisation

University Health Network, University of Toronto


Principal Investigators:

  • Professor Ewan Goligher, University Health Network, University of Toronto
  • Professor Patrick Lawler, University Health Network, University of Toronto
  • Professor Ryan Zarychanski, University of Manitoba

Potential of repurposed therapeutic for COVID-19 pandemic

Severe cases of COVID-19 are associated with the formation of blood clots in the lungs and other organs. This can affect both large and small blood vessels, blocking oxygen supply to the body and can result in death.

Heparin is widely used in hospitals as an anticoagulant, helping to prevent the formation of blood clots in at-risk patients. Several studies have also shown heparin to have anti-inflammatory properties which may help limit virus-induced inflammation. Whilst clinical benefits of heparin’s antiviral properties have not yet been determined, it has also been shown to interfere with SARS-CoV-2 cell invasion in lab studies by interfering with viral attachment to cells.

LifeArc has chosen to focus its funding on drugs such as heparin because it is an inexpensive, highly accessible, and widely used generic drug that, if shown to work, can be available to patients much faster than any newly developed drug.

LifeArc and the LifeArc COVID-19 Fund Scientific Advisory Board reviewed existing data from previous animal and safety studies. They also conducted due diligence and assessed the research plan. The successful researchers intend to conduct a multi-site adaptive clinical trial to determine if heparin can improve outcomes of hospitalised COVID-19 patients. The aim is to reduce the number who need to be put on a ventilator or who die because of the infection. The clinical trial will take place over 6-9 months at multiple sites using the ATTACC Trial Network in Canada as well as sites in USA, Mexico, and Brazil. The trial has commenced enrolment and is rapidly recruiting patients.