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Syncope and implantable loop recorders: Good value for money?

September 01, 2009

The REVISE Study (Reveal in the Investigation of Syncope and Epilepsy) found that 1 in 8 adult patients in the United Kingdom, previously thought to be suffering from epilepsy or in whom this diagnosis was in doubt, in fact had symptoms as a result of an abnormal pattern of heart beating, commonly found in patients with syncope (fainting).

REVISE is the first study to show that, by means of an implantable ECG recorder, 1 in 8 patients who were previously thought to have epilepsy or in whom this diagnosis was in doubt, have an abnormality in their heart rhythm as a cause of their symptoms. Eighty percent of those who underwent a pacemaker insertion based on the results of the ECG loop recorder were subsequently found to be free of their symptoms.

Four of the 5 patients who underwent a pacemaker as part of this study were subsequently free of symptoms. The average duration of follow-up was 9 months. This study was carried out at the Manchester Heart Centre, Manchester Royal Infirmary, Manchester, UK in collaboration with the Greater Manchester Centre for Neurosciences, Hope Hospital, Salford, UK. A small metallic device * about the size of a memory stick or a packet of gum, was used to record the heart rhythm of patients in this study. This device was inserted underneath the skin, on the left side of the chest in a small, low risk, 20 minute operation. Study patients also underwent a number of other brain and heart tests.

Previous scientific studies, mainly from the United Kingdom, have shown that up to 1 in 4 patients thought to be suffering from epilepsy do not actually have this condition. This conclusion was based on reviewing medical records of patients known to have epilepsy and on the results of the tilt table test, a test in which patients are made to stand at an angle of 60 degrees on a bed with a footboard support in an attempt to induce a blackout. Moreover, the All Party Parliamentary Group on Epilepsy, in their report published in June 2007, found that 74,000 patients in the United Kingdom were taking drugs for epilepsy, which they did not need. Patients with syncope (fainting) as well as epilepsy present with transient loss of consciousness (T-LOC) or 'blackouts'. In some patients syncope (fainting) can mimic epilepsy. A temporary decrease in blood supply to the brain which occurs in syncope (fainting) can result in irritation of brain cells causing abnormal movements, which to a lay person can look very similar to epilepsy. In the general population, syncope (fainting) is much more common than epilepsy, affecting 25% of the population at any given time, more so in the elderly.

Patients symptomatic with T-LOC/'blackouts' were considered for inclusion in this study if on review by the neurologists there was a suspicion of misdiagnosis of epilepsy or there was a doubt regarding the diagnosis. Patients had to have suffered at least 3 blackouts in the year before enrolment. In addition, they had to have had a normal or equivocal recording of their heart rhythm (standard ECG and an external recording for at least 24 hours), brain waves (EEG), a scan of the heart (echocardiogram) and of the brain (CT scan or MRI). Once included, all patients underwent a Reveal® Plus/Reveal® DX implant for monitoring their heart rhythm and tilt table testing. The study protocol allowed for treatment, based on the results of the implantable ECG monitor. The main aim of the study was to record the heart rhythm at the time of the patients symptoms of T-LOC/blackouts by means of the implantable ECG monitor. This study also aimed to determine the value of the tilt table test, a test commonly used in the investigation of patients with T-LOC/blackouts, in this group of patients.

Of the 119 patients screened, 40 were found suitable for inclusion in the study. Two thirds of patients were females and the average age was 39 years. The oldest patient in the study was 80 years of age. The implantable ECG monitor recorded a heart rhythm at the time of symptoms in two thirds of patients. Six patients were found to have an abnormal heart rhythm, viz. severe slowing of the heart beats, to the point of an absent heart rhythm, for a few seconds. In four other patients, the heart rhythm was found to slow but not as severely as the previous group. In 4 others, the implantable ECG monitor recorded signals due to muscle shaking in a pattern commonly seen in patients with epilepsy, thus giving the doctors a clue to the diagnosis. All but one of the six patients with severe slowing of the heart beats underwent a pacemaker. Four of the five (80%) who had pacemakers were subsequently free of symptoms over the following 9 months. Tilt table testing was positive in 5 of 40 patients. None of the patients with a positive tilt table test showed severe slowing of the heart rhythm on the implantable ECG monitor.

REVISE is the first study to show, that by means of an implantable ECG recorder, 1 in 8 patients who were previously thought to have epilepsy or in whom this diagnosis was in doubt, have an abnormality in their heart rhythm as a cause of their symptoms. Eighty percent of those who underwent a pacemaker insertion based on the results of the ECG loop recorder were subsequently found to be free of their symptoms. The implantable ECG loop recorder was also helpful in pointing towards a diagnosis of epilepsy by the pattern of the signals recorded on it. The findings of this small study will need confirmation in a larger group of patients.

European Society of Cardiology