Study shows fainting factor in cardiac arrests


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For Immediate Release:
February 9, 2012          

(LONDON, Ontario) – Up to 45,000 sudden cardiac arrests occur each year in Canada, and less than five percent survive. In some of these cases, the event cannot be explained by the presence of underlying heart disease. In order to identify people at risk of these unexplained cardiac events, a newly published study examined the presence of certain warning symptoms that are present in people who have been resuscitated from a cardiac arrest. The research found that over a quarter of unexplained cardiac arrests occurred after the patient had an event of fainting, known as syncope. Patients also had frequent chest pain and palpitations.

Conducted by Dr. Andrew Krahn, Cardiologist, London Health Sciences Centre, Scientist, Lawson Health Research Institute, and Professor, The University of University of Western Ontario, and colleagues from across Canada, the study involved clinical evaluation of patients with apparently unexplained cardiac arrest and no evident cardiac disease and included patients and first-degree relatives.

Symptoms represent an opportunity for detection of risk and possible prevention when assessed by the health care team. More than half of the fainting episodes had characteristics that would point to a serious heart rhythm problem, based on a simple fainting questionnaire that can be administered in a doctor’s office or emergency room, developed in Calgary by Dr. Robert Sheldon.

“The research and study findings suggest that fainting may be one signal that could be used to identify and prevent future events,” Krahn explains. “Warning symptoms like fainting provide an opportunity to diagnose genetic disorders that may lead to treatment to prevent future sudden death.

The study and Dr. Krahn was supported by the Heart and Stroke Foundation of Ontario, representing a strong commitment to detection and prevention of risk of sudden death.

“Funding research like Dr. Krahn's is a great example of how Heart and Stroke Foundation is continuing to save lives,” said Vincent Bowman, Director of Research, Heart and Stroke Foundation of Ontario "Helping the public better understand the relationship between fainting and sudden death may encourage people to quickly seek the help they need to diagnose the presence of a serious heart arrhythmia.”

The study, Sentinel Symptoms in Unexplained Cardiac Arrest, is published in Journal of Cardiovascular Electrophysiology at:

Further information on inherited rhythm disorders can be found at:


About London Health Sciences Centre

London Health Sciences Centre has been in the forefront of medicine in Canada for 137 years and offers the broadest range of specialized clinical services in Ontario. Building on the traditions of its founding hospitals to provide compassionate care in an academic teaching setting, London Health Sciences Centre is home to Children’s Hospital, South Street Hospital, University Hospital, Victoria Hospital, Fowler Kennedy Sports Medicine Clinic, two family medical centres, and two research institutes – Children’s Health Research Institute and Lawson Health Research Institute, a joint research initiative with St. Joseph’s Health Care, London. As a leader in medical discovery and health research, London Health Sciences Centre has a history of over 50 international and national firsts and attracts top clinicians and researchers from around the world. As a regional referral centre, London Health Sciences Centre cares for the most medically complex patients including critically injured adults and children in Southwestern Ontario and beyond. The hospital’s nearly 15,000 staff, physicians, students and volunteers provide care for more than one million patient visits a year. For more information visit

About Lawson Health Research Institute

As the research institute of London Health Sciences Centre and St. Joseph's Health Care, London, and working in partnership with The University of Western Ontario, Lawson Health Research Institute is committed to furthering scientific knowledge to advance health care around the world.

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Rachelle Wood
Corporate Communications and Public Relations
London Health Sciences Centre
519-685-8500, ext. 77642

Sonya Gilpin
Communications & Public Relations
Lawson Health Research Institute
519-685-8500, ext. 75852


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