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Study shows “black box” heart device accurate and cost-effective for diagnosing mysterious blackouts


London, ON August 8, 2003 – The use of a small, implantable monitor in patients who experience episodes of unexplained fainting (syncope) can lead to a diagnosis at a lower cost than conventional testing strategies, according to a study published in this week’s issue of Journal of the American College of Cardiology.

“People who suffer from mysterious fainting episodes often live in fear that the next time it happens, they could be seriously hurt,” says Dr Andrew Krahn, the study’s principal investigator and associate professor in the division of cardiology at the University of Western Ontario. “Our research shows that this device is both a cost-effective and accurate diagnostic tool for many patients.”

Invented and developed in Canada, the Medtronic Reveal Plus insertable loop recorder is an implantable cardiac monitor that records the heart’s rate and rhythm at the time of an unexplained syncopal episode. Placed just under the skin of the chest area using local anesthesia during a simple outpatient procedure, the monitor performs a function similar to that of a black box on an airplane, recording important data that can be saved and evaluated later to determine a diagnosis. It continuously monitors and can record the heart’s electrical activity for up to 14 months. The Reveal Plus monitor may help diagnose whether symptoms like fainting, dizziness, palpitations and unexplained seizure-like episodes have a cardiovascular cause, or if the patient should be referred to another specialist, such as a neurologist.

To evaluate the benefits of the insertable monitor, investigators at the University of Western Ontario conducted a randomized clinical trial in 60 patients who were undergoing cardiac testing for unexplained fainting. Of the patients who received the monitor, 47% were successfully diagnosed, while only 20% who received conventional testing were accurately diagnosed. In new cost-effectiveness data published this week, the cost-per-diagnosis in those who were randomized to receive one year of monitoring with the monitor was 30% less than the cost-per-diagnosis in those who received conventional testing.

The study authors concluded that the monitor should be considered as an early-stage diagnostic tool for people without major structural heart disease who experience unexplained fainting spells. “We’ve already seen evidence that the insertable loop recorder is an effective tool for identifying why many people have syncopal episodes,” says Dr Krahn. “Now, we have also demonstrated a substantial cost savings related to use of the small implanted monitor compared to conventional diagnostic strategies that are often inconclusive.”

Syncope is a major diagnostic challenge for physicians and a widespread medical concern. Half of the population blackout at some time and 3% of those are recurrent and unexplained. Syncope accounts for up to 6% emergency room visits and 2% of all hospital admissions. The condition can lead to bodily injury caused by falls, or accidents associated with driving or operating machinery. In addition, patients who experience syncope may have serious underlying cardiac conditions and may be at risk of further harm or even death if the condition remains undiagnosed.

In another study about the diagnosis of syncope published in The New England Journal of Medicine in September 2002, researchers found that 10% of study participants with cardiac syncope would have died in six months without proper diagnosis and treatment for their cardiac condition.

Since its approval in 1997, close to 1,100 Medtronic Reveal monitors have been implanted in Canadians across the country.