A new device that records cardiac rhythm for seven days can identify atrial fibrillation in 1 of 18 stroke patients in whom two standard tests failed to detect the arrhythmia, according to an article in the May 21st rapid access issue of Stroke. The device, called an event-loop recording, is triggered by an irregular heart rhythm to store data; data are eventually downloaded and interpreted by computer.

“Atrial fibrillation accounts for 15 to 20 percent of all strokes,” said lead author Denis Jabaudon, MD, PhD, of Geneva, Switzerland.

Patients also can trigger the device if they experience palpitations or dizziness. Interestingly, patient records indicated that palpitations were rarely indicative of underlying atrial fibrillation.

Project leader Roman Sztajzel, MD, noted that atrial fibrillation is often asymptomatic, with stroke the first clinical evidence of arrhythmia. Because up to 30 percent of patients with atrial fibrillation have only transient episodes of irregular heart rhythm, the diagnosis can easily be missed with standard electrocardiography (ECG) or even 24-hour recording with a Holter monitor.

“It is important to find everyone with atrial fibrillation, because they are at high risk of a second stroke and anti-clotting drugs can dramatically reduce that risk,” Sztajzel said.

In the current study, a team of cardiology and neurology researchers investigated whether long-term recording of cardiac rhythm in patients several days after a stroke would detect otherwise-hidden cases of atrial fibrillation. Among 149 consecutive patients hospitalized for stroke or transient ischemic attack, standard ECG identified atrial fibrillation in 10 patients within five days of initial hospitalization.

Holter monitoring of the remaining 139 patients identified 7 additional patients with atrial fibrillation. Patients with normal ECG and Holter findings underwent seven-day monitoring an average of 55 days after hospital admission. The longer-term event-loop recording identified atrial fibrillation in 5 of 88 patients (5.7 percent) for whom complete data were available.

“If the event-loop recording test had not been done, these patients could not have been treated (with anticoagulation) and would have remained at high risk for another stroke,” Sztajzel said.

At the present time, event-loop recording devices are used clinically in Europe and the United States for investigation of syncopal episodes and unexplained chest pain. Prior to the current study, the devices had not been used in standard stroke examinations, according to the authors.

The authors wrote, “This study indicates that ECG, Holter, and event-loop recording should be used sequentially to provide the best opportunity to identify the most atrial fibrillation patients.”

Detecting atrial fibrillation is an important aspect of stroke management, and stroke care in the United States typically includes cardiac monitoring to detect it, said Robert J. Adams, M.D., an American Stroke Association spokesperson: “If these findings are confirmed in other studies of similar patients and 6 percent more atrial fibrillation patients are identified, this may well be worth incorporating into widespread practice, especially if predictors can limit the target group that should undergo extended monitoring,” Adams said.