Implantable ECG Loop Recorder Differentiates Between Syncope and Epilepsy

Fran Lowry

September 10, 2009

September 10, 2009 (Barcelona, Spain) — The diagnosis of epilepsy and syncope are all too often confused, resulting in unnecessarily high monetary, medical, and emotional costs to misdiagnosed patients. Now, results from a small study presented at the European Society of Cardiology (ESC) 2009 Congress show that use of an implantable ECG loop recorder that recognizes the distinctive heart rhythms of both conditions while they are occurring can aid in making the right diagnosis.

Dr. Sanjiv Petkar

The Reveal in the Investigation of Syncope and Epilepsy (REVISE) study found that one in eight patients who were previously thought to have epilepsy or in whom this diagnosis was in doubt actually had an abnormality in their heart rhythm as a cause of their fainting, thanks to the loop recorder, Dr Sanjiv Petkar (Castle Hill Hospital, Kingston-Upon-Hull, UK) said. When they received a pacemaker, based on the results of the loop recorder, their symptoms disappeared.

The new ESC guidelines for the management of syncope now recognize the utility of implantable loop recorders in diagnosing this condition [1]. They state that the recorders, which have a battery life of up to three years and a memory that stores ECG recordings, have been shown to be cost-effective in the diagnosis of unexplained syncope, with a high correlation between symptoms and stored ECG data.

Thousands Taking Antiepileptic Drugs Needlessly

Studies have shown that about one in four people with epilepsy are misdiagnosed, Petkar explained to heartwire . "When there is a decrease in blood supply to the brain, which occurs with syncope or fainting, there is irritation of the neurons in the brain, and this can cause abnormal movements that can be misinterpreted by laypersons as epilepsy," he said. "In the UK, we estimate that 15 million people have fainted at some point in their lives, whereas we estimate that the number of people with epilepsy is between 300 000 to 600 000, so their number is much lower."

Epilepsy is a terrible thing to have, but to not have it and think you have it is equally terrible.

In June 2007, a report by the All Party Parliamentary Group on Epilepsy found that 74 000 people were taking epilepsy drugs unnecessarily. And once there is a diagnosis of epilepsy, there are direct medical costs as well as indirect costs. The annual medical cost of epilepsy misdiagnosis is £29 million per year, and the indirect cost is £138 million per year, Petkar said.

"The cost to society is huge, and the personal cost is quite significant--loss of employment, loss of self-esteem, lost productivity, driving restrictions, young women of child-bearing age taking antiepileptic drugs when they don't need to and having fetal abnormalities. It's such a waste," he commented.

Starting with the hypothesis that the common alternative diagnosis in patients with a misdiagnosis of epilepsy is convulsive syncope, Petkar and his colleagues thought the implantable loop recorder would be useful in confirming a diagnosis because it would capture an event as it occurred.

Patients who suffered transient loss of consciousness or blackouts and in whom a misdiagnosis of epilepsy was suspected or whose diagnosis of epilepsy was doubted by a neurologist were included in the study.

Patients had to have had at least three episodes of transient loss of consciousness in the past 12 months and a normal, equivocal, or nondiagnostic 12-lead ECG, echocardiogram, 24-hour ECG, standard unprovoked EEG, and brain CT or MRI. The study included 41 patients (15 males, 26 females; median age 39 years, range 18 to 80 years), whose duration of symptoms ranged from 12 to 540 months (median 96 months). More than half of the patients--24 of 41 (58.5%)--were on two or more antiepileptic drugs

ECG-symptom correlation was achieved in 29 (70.7%) of patients.

Implantable loop-recorder findings in 29 patients

Implantable loop-recorder findings Patients, n (%)
Normal sinus rhythm 18 (62.1)
Asystole 7 (24.1)
Muscle artifacts suggestive of tonic-clonic seizures 4 (13.8)


The mean length of asystole was 25.4±30.3 seconds (median 11.2 seconds; range 4 to 89 seconds). Six of the seven patients with asystole underwent permanent pacemaker implantation as a result of the loop-recorder findings, and five of them remained asymptomatic over the following nine months.

In addition, the loop recorder showed signs of epilepsy in four patients, thus giving doctors a clue to their diagnosis. Two of these patients were started on antiepileptic medication.

Of the 24 patients who were taking antiepileptic drugs at the start of the study, eight stopped taking them, and six remained asymptomatic on withdrawal.

If in Doubt, Ask a Cardiologist

Neurologists should take a step back and ask themselves whether everyone they see with recurring symptoms truly has epilepsy, Petkar told heartwire . "If they are convinced, that is fine, but if they have doubts, they should ask a cardiologist for an opinion. This is where we need more cooperation between the cardiologist and the neurologist. Because epilepsy is a terrible thing to have, but to not have it and think you have it is equally terrible."

Commenting on the study to heartwire , Dr Martin Jan Schalij (University Hospital, Leiden, the Netherlands) agreed that it was important to include the loop monitor in the total workup of patients with syncope of unknown origin. "I believe 40% of all people younger than 40 years will have one episode of syncope in their life, and a lot of them are treated automatically with epilepsy drugs. If it is possible to search for cardiac causes or arrhythmias by other means, that should be done, so you should not implant such a recorder in every patient. But in some patients, it may help you to distinguish between epilepsy and cardiac causes or something else."

The study was funded by Medtronic.


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