News Release 

Intravenous drugs can often rapidly restore normal heart rhythm without sedation, shocks

Clinical trial published in The Lancet first to compare two kinds of rapid cardioversion for acute atrial fibrillation

The Ottawa Hospital

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IMAGE: A study led by Dr. Ian Stiell published in The Lancet found that two ways of quickly restoring normal heart rhythm in patients with acute atrial fibrillation in the emergency... view more 

Credit: The Ottawa Hospital

A study published in The Lancet found that two ways of quickly restoring normal heart rhythm in patients with acute atrial fibrillation in the emergency department are equally safe and effective.

The large, randomized controlled trial looked at cardioversion, a medical procedure that quickly brings heart rhythm back to normal. Cardioversion can be done with a mild electric shock or with fast-acting drugs delivered through an IV.

"These methods allow us to quickly get patients back to their normal heart rate, and send them home after four to six hours in the emergency department," said Dr. Ian Stiell, lead author and senior scientist at The Ottawa Hospital and distinguished professor at the University of Ottawa.

Acute atrial fibrillation is a rapid, irregular heartbeat that must be treated within 48 hours to avoid complications like stroke and heart failure. The study team estimates that acute atrial fibrillation accounts for 430,000 emergency department visits every year in Canada and the United States.

The researchers recruited 396 patients with acute atrial fibrillation from 11 Canadian emergency departments. Cardioversion is a commonly used treatment in this country. Patients were randomly assigned to one of the two kinds.

The first group received only electrical cardioversion. Patients are sedated during this procedure, so they do not feel the shock.

The second group received a drug called procainamide through an IV. If the drug did not reset the patient's heart rhythm within 30 minutes, they received electrical cardioversion.

In the shock-only group (192 patients):

  • 92 percent returned to their normal heart rhythm (176)

  • 95 percent were discharged home (183)

In the drug-then-shock group (204 patients):

  • 96 percent returned to their normal heart rhythm (196)

  • 97 percent were discharged home (198)

  • 52 percent recovered their normal heart rhythm with the drug alone (106)

Both kinds of cardioversion were equally good at restoring normal heart rhythm and getting patients home the same day. The drug-shock strategy was more effective for patients experiencing atrial fibrillation for the first time, and for patients younger than 70.

The two methods were equally safe -none of the patients had any serious side-effects. Two weeks after the treatment, no patients had had a stroke, 95 percent still had normal heart rhythm, 11 percent returned to the emergency department because of atrial fibrillation, three percent had an additional round of cardioversion, and two percent were admitted to hospital.

The researchers were interested to see that over half of the patients who received the drug did not need a shock to restore their regular heart rhythm. They recommend that physicians try the drug cardioversion first, to avoid unnecessary sedation.

"If I have a patient on a drug infusion, I can see other patients at the same time," said Dr. Jeffrey Perry, study co-author and senior scientist at The Ottawa Hospital and professor at the University of Ottawa. "To do an electrical cardioversion, I need to find another doctor, a nurse and a respiratory therapist, and it takes time to assemble those people."

The researchers note that patients often have a strong preference for one kind of cardioversion over the other, especially if they need it done regularly.

"While we believe that there are advantages to trying the drug infusion before the shock, the treatment choice is ultimately a shared decision between the patient and physician," said Dr. Perry.

While cardioversion is common in Canada, it isn't as well known in other parts of the world.

"In some countries, patients with acute atrial fibrillation are sent home with pills to slow their heart rate, while others are admitted to hospital," said Dr. Stiell. "Our study showed that cardioversion in the emergency department is safe and effective. We hope our results convince more physicians around the world to adopt these methods."

"Given the crowding which exists in the emergency health care setting, the Canadian Institutes of Health Research (CIHR) is proud to support this high-quality research that enhances evidence-informed clinical decisions in the transitions of care for patients with atrial fibrillation," said Dr. Brian Rowe, study co-author, Scientific Director of the CIHR's Institute of Circulatory and Respiratory Health, and professor of emergency medicine at the University of Alberta.

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Reference: Electrical versus pharmacological cardioversion for emergency department patients with acute atrial fibrillation (RAFF2): a partial factorial randomised trial. Ian Stiell, Marco Sivilotti, Monica Taljaard, David Birnie, Alain Vadeboncoeur, Corinne Hohl, Andrew McRae, Brian Rowe, Robert Brison, Venkatesh Thiruganasambandamoorthy, Laurant Macle, Bjug Borgundvaag, Judy Morris, Eric Mercier, Catherine Clement, Jennifer Brinkhurst, Connor Sheehan, Erica Brown, Marie-Joe Nemnom, George Wells, Jeffrey Perry. The Lancet. January 30, 2020.

Core Resources: Ottawa Methods Centre

Funding: This study was supported by the Canadian Institutes of Health Research and the Heart and Stroke Foundation of Canada. Research at The Ottawa Hospital is possible because of generous donations to The Ottawa Hospital Foundation.

About The Ottawa Hospital: The Ottawa Hospital is one of Canada's top learning and research hospitals, where excellent care is inspired by research and driven by compassion. As the third-largest employer in Canada's capital city, our support staff, researchers, nurses, physicians, and volunteers never stop seeking solutions to the most complex health-care challenges. Our multi-campus hospital, affiliated with the University of Ottawa, attracts some of the most influential scientific minds from around the world. Backed by generous support from the community, we are committed to providing the world-class, compassionate care we would want for our loved ones. http://www.ohri.ca

About the University of Ottawa --A crossroads of cultures and ideas: The University of Ottawa is home to over 50,000 students, faculty and staff, who live, work and study in both French and English. Our campus is a crossroads of cultures and ideas, where bold minds come together to inspire game-changing ideas. We are one of Canada's top 10 research universities--our professors and researchers explore new approaches to today's challenges. One of a handful of Canadian universities ranked among the top 200 in the world, we attract exceptional thinkers and welcome diverse perspectives from across the globe. http://www.uottawa.ca

About the Canadian Institutes of Health Research (CIHR): The Canadian Institutes of Health Research (CIHR) recognizes that research has the power to change lives. As Canada's health research investment agency, CIHR collaborates with partners and researchers to support the discoveries and innovations that improve our health and strengthen our health care system.

About Heart & Stroke: Life. We don't want you to miss it. That's why Heart & Stroke leads the fight against heart disease and stroke. Together, we are working to prevent disease, save lives and promote recovery through research, health promotion and public policy. (heartandstroke.ca)

Media Contact: Amelia Buchanan, Senior Communication Specialist, Ottawa Hospital Research Institute; ambuchanan@ohri.ca; Office: 613-798-5555 x 73687; Cell: 613-297-8315

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