Event loop recorder helps detect atrial fibrillation

The device offers numerous advantages over a Holter monitor, including a seven-day recording duration.

The longer and continuous recording duration of an event loop recorder may offer physicians the advantage of recording paroxysmal and often silent episodes of atrial fibrillation that would not be identified by use of a Holter monitor.

An event loop recorder (ELR) such as the Lifecard CF from Del Mar Reynolds Medical, Irvine, Calif., offers distinct advantages over the “classical” ambulatory electrocardiogram. Unlike Holter monitors used for 24 to 48-hour recordings, the Lifecard CF makes much longer recordings possible by storing up to seven days of cardiac rhythm information. It also offers a manual or “patient-triggered” recording function in addition to its automatic recording capabilities.

“The ELR is probably still used much less than the standard Holter recorder,” said Juan Sztajzel, MD, at the Cardiology Center, University Hospital Geneva. Sztajzel believes, however, that the ELR should be of great interest to physicians.

“Because of the growing age of our population and the related potential risk of an increased incidence of AF during the coming years, we will need to use such a type of device in order to improve our detection of this arrhythmia,” Sztajzel told Cardiology Today.

Detecting AF

Sztajzel and his colleagues studied the usefulness of the device for the detection of AF and atrial flutter after acute stroke and transient ischemic stroke. If there was no AF after an admission ECG, patients were given a second ECG 24 hours later. Again, if no AF was present, they proceeded to a Holter monitor for 24 hours of monitoring. If there was still no AF, outpatients were monitored for seven days using the Lifecard CF.

The Lifecard CF 7-day event loop recorder from Delmar Reynolds can record ECG data for up to seven days. Photos courtesy of Del Mar Reynolds Medical

Of the 149 patients studied, 127 were in sinus rhythm and 22 were in AF. Patients with AF were significantly older (72 years vs. 66 years) and had more history of paroxysmal AF (23% vs. 16%) and atrial enlargement (43% vs. 11%).

“In our study, the ELR detected AF in about one in 20 patients in whom standard ECG and Holter were normal,” Sztajzel said.

According to Sztajzel, the Lifecard CF is easy to use. It is usually attached by a technician to the patient’s chest. The patient is instructed to use the manual recording function each time they experience symptoms, and the device is returned after one week.

“The only disadvantage I would see is the fact that the device has to be worn by the patient for a longer time, at least seven days. However, the device is small, it is not noisy and the patient can take it off at any moment when he wishes to,” Sztajzel said.

Two to three self-adhesive electrodes are used, and patients can remove the electrodes to bathe. Sztajzel said that he gives his patients additional electrodes so that they can be changed if necessary.

Analyzing data

The results of the ELR are not difficult to interpret, Sztajzel said. After the stored data are transferred to a computer system, they can be analyzed. “The duration to analyze a single one-week recording is about 45 minutes for an experienced cardiologist,” he said.

“We give special training for ELR analysis which consists of learning how to program different rhythm modalities so that the device may recognize and detect the arrhythmia we are looking for,” Sztajzel said. “For the particular detection of AF, the ELR is programmed to store irregular RR-strips which may correspond to this arrhythmia. The analyzing physician must be able to recognize artifacts and remove them from the recording.”

Analyzing ELR results is when the manual recording function offers its real advantage. During periods when a patient is experiencing specific symptoms such as palpitations or dizziness, they can punch a key on the device; this will drop a clear arrow marker into ECG recording that will directly correspond to the moment when the symptoms occurred. Highlighting these patient-triggered moments can be especially useful for a cardiologist in detecting AF.

Additionally, analyzing an ELR recording costs the same as analyzing a standard 24-hour Holter tape.

Given that the incidence of stroke in Switzerland is about 150 per 100,000 patients, “if we use this small device, we may detect approximately 600 cases of AF per year, with the potential prevention of 50 strokes per year,” Sztajzel said. – by Evan Young

For more information:

• Sztajzel J. Atrial fibrillation and flutter after acute stroke and transient ischemic attack: ambulatory 7-day ECG monitoring. Presented at the European Chapter meeting of the Vascular Biology Working Group. Aug. 27, 2004. Munich, Germany.