Study shows drugs can often restore heart rhythm without shocks or sedation

Posted on Thursday, January 30, 2020

Dr. Stiell in a hospital room.

"We hope our results convince more physicians around the world to adopt these methods.”

-- Dr. Ian Stiell, uOttawa distinguished professor and senior scientist at The Ottawa Hospital

In the emergency room, patients with acute atrial fibrillations need rapid relief.

In Canada, that relief is often provided by a mild electric shock that restores normal heart rhythm, or with intravenous drugs. But no clinical study had ever compared the safety and effectiveness of the two methods.

Now, a clinical trial led by Dr. Ian Stiell, uOttawa distinguished professor and senior scientist at The Ottawa Hospital, has found that intravenous drugs can restore heart rhythm in more than 50 percent of patients without the need for electric shocks — saving both time and resources.

“If I have a patient on a drug infusion, I can see other patients at the same time,” said study co-author Dr. Jeffrey Perry, 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.”

Given the study’s results, the researchers recommend that physicians try the drug treatment first, to avoid unnecessary sedation.

“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.

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. 

In Canada, acute atrial fibrillation is commonly treated by cardioversion, a medical procedure that quickly brings heart rhythm back to normal. Cardioversion can be done with a mild electric shock while the patient is under sedation, or with fast-acting drugs delivered through an IV, with no sedation required.

The randomized controlled trial led by Dr. Stiell is the first study to compare the two different kinds of cardioversion for safety and effectiveness.

The researchers recruited 396 patients with acute atrial fibrillation from 11 Canadian emergency departments. Patients were randomly assigned to one of two groups. The first group received only electrical cardioversion. 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, the patient then 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)

Overall, the study showed that both forms of cardioversion are safe and effective. None of the patients experienced serious side-effects

“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. Stiell.

 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.”

Read the complete press release from The Ottawa Hospital.

Dr. Stiell tends to a patient

Dr. Stiell’s work focuses on clinical decision rules for emergency medicine.


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