Europace: Implantable loop recorder helps avoid numerous tests for syncope (Update)

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Many patients with unexplained syncope eventually were diagnosed with an implantable loop recorder, but only after nearly a dozen prior tests, supporting current guidelines that these devices should be implanted early rather than late in the evaluation of unexplained syncope, according to a study published online Nov. 19 in EP-Europace.

“Syncope is common in the general population and is perceived as an important clinical problem with adverse outcomes from associated physical trauma, negative impact on quality of life and an increased cardiovascular risk in many patients,” the authors wrote.

Nils Edvardsson, MD, PhD, from Sahlgrenska University Hospital in Göteborg, Sweden, and colleagues conducted the PICTURE (Place of Reveal In the Care Pathway And Treatment of patients with Unexplained Recurrent SyncopE) trial, a prospective, multicenter, observational study conducted between 2006 and 2009 in 10 European countries and Israel.

While the gold standard of care remains the “correlation of a spontaneous event with a specific ECG finding,” observers often do not have an opportunity to record ECGs at the time of an event. Loop recorders are tools which can continuously record ECGs and have longevity of up to three years, making them a viable tool for diagnosing syncope.

"We believe that if patients could get to this new technology—the implantable loop recorder—earlier they would also come sooner to a diagnosis," Edvardsson, told Cardiovascular Business News. "When we look at the yield of the device, which is very different over time, most of the patients had a cardiovascular cause of symptoms.

"When these intermittent syncope attacks come, you have stored ECG data so that you have a correlation between symptoms and the rhythm that was actually present," Edvardsson noted.

The 650 patients enrolled in the PICTURE registry were evaluated by three difference specialists for syncope management and underwent a mean of 13 tests. All patients received a Reveal Plus (45 percent of patients) or Reveal DX/XT (55 percent of patients) (Medtronic) and follow-up data was available for 570 patients. The researchers followed up with patients until the first recurrence of syncope that lead to a diagnosis or for one year. The average follow-up time after an implant was 10 months.

The device is placed just under the skin of the chest area in an outpatient procedure and captures and stores ECG recordings in two ways: a patient-activated feature allows the patient to press a button and store an ECG recording during a symptomatic episode, and an auto-activation feature automatically detects and records predefined arrhythmic events. Later, a physician analyzes the stored information, which can be transmitted remotely via the CareLink Network (Medtronic) or viewed during an in-office patient visit.

Patients had an average age of 61 and 54 percent were women, seven percent had unexplained pre-syncope and 91 percent had unexplained syncope. Classification was missing for 2 percent of patients.

In the course of the study, patients were evaluated by an average of three different specialists for management of their syncope and underwent a median of 13 tests without providing a conclusive diagnosis. Significant physical trauma had been experienced in association with a syncopal episode by 36 percent of patients.

At three, six and 12 months, the percentage of patients with recurrent syncope was 19, 26 and 36 percent, respectively. Of 218 events within the study, loop recorder-guided diagnosis was obtained in 170 cases, of which 128 were cardiac,representing 59 percent of all recurrences of syncope.

“Reveal played a role in the diagnosis and showed the recurrence of diagnosis within 180 days as 20 percent, within 365 days as 30 percent, and within 462 days as 38 percent,” the authors wrote. “The estimated rate of syncope after 30 days of follow-up was 10 percent and the estimated rate of diagnosis where Reveal played a role at this time of follow-up was 9 percent.”

Implantable loop recorder-guided diagnoses led to pacemaker implants in 51 percent of diagnosed cases. Antiarrhythmic drug therapy (7 percent), other pharmacologic treatment (5 percent), implantable cardioverter-defibrillators (6 percent) and ablation (5 percent) were also prescribed treatments.

In less than 20 percent of patients with a recorder-guided diagnosis, physicians decided to undertake no specific treatment. "In this group of patients, the benefit of knowing the cause of syncope would have reduced the need for further diagnostic tests. This finding implies that many tests undertaken prior to implant were unnecessary in that they had a low probability of reaching a diagnosis," investigators wrote.

“The results of the PICTURE study provide new and important insights into the discrepancy between real-life care and the recommendations in the ESC guidelines at the time,” the authors noted. “The results underline that more efforts are needed if better adherence to guidelines are to be obtained.”

Edvardsson told Cardiovascular Business News that there are a limited number of syncope clinics around the world. Due to this fact, when patients have fainting spells, they go to their nearest institution for care and "could have a number of tests performed that do not necessarily lead to a quick diagnosis."

In PICTURE, nearly half of the patient population had undergone an MRI or CT scan, neurological evaluation or psychiatric evaluation. In previous syncope studies, this figure was around 20 percent.

"Cardiologists were often seen, both as the first and the last specialist before implant. These observations must lead to the question how to make the first contact with a cardiologist more useful, since the final diagnosis is most often to be found in his/her area of competence," the authors wrote.

"There is much more physician education to be done," Edvardsson said. "Studies like this help but there is still a challenge because the reasons for syncope are so diverse that this information has to reach cardiologists, neurologists, psychiatrists, emergency department doctors and more to penetrate the field," he concluded.

The latest generation Reveal XT can detect atrial fibrillation and all iterations of the device are MRI compatible.

Minneapolis-based Medtronic sponsored the PICTURE trial and several study authors listed conflicts of interests with Medtronic.