Nearly one-third of patients with a stroke of unknown cause have a heart rhythm disorder that can be treated to prevent another stroke. That is the conclusion of the NOR-FIB study presented at EHRA 2022, a scientific congress of the European Society of Cardiology (ESC).
In the study, stroke patients had their heart rhythm monitored for 12 months with a tiny implanted device. “More than 90% of stroke patients who had atrial fibrillation had no symptoms of the heart rhythm disorder,” said study author Dr. Barbara Ratajczak-Tretel, of Østfold Hospital Trust, Sarpsborg, Norway. “For many patients, atrial fibrillation would not have been diagnosed or treated without ongoing monitoring, putting them at risk for another stroke.”
Most strokes are ischemic, meaning that a blockage stops blood flow to the brain. In about one in four ischemic strokes, the cause is undetermined. “The best therapy to prevent another stroke depends on the underlying cause,” said Dr. Ratajczak-Tretel. “Those with atrial fibrillation should receive oral anticoagulants, but a definitive diagnosis is needed before these medications can be prescribed. Atrial fibrillation can be transient and asymptomatic, making it difficult to detect.
The Nordic Atrial Fibrillation and Stroke (NOR-FIB) study examined the ability of one-year continuous heart rate monitoring with an implanted device to identify atrial fibrillation in patients with an ischemic stroke or mini-stroke (transient ischemic attack). ; AIT) of unknown origin. etiology.
The prospective observational study included 259 patients with no documented history of atrial fibrillation from 18 centers in Norway, Denmark, and Sweden. All patients received a cardiac monitor, which was implanted a median of nine days after the stroke or TIA. The device is one-third the size of a AAA battery and was inserted subcutaneously over the heart under local anesthesia.
Data from the device was automatically transmitted over a secure network to a central laboratory of two neurologists and two cardiologists and evaluated once a week. When atrial fibrillation lasting at least two minutes was detected, the central laboratory contacted the patient’s doctor, who then prescribed oral anticoagulants. The patients were followed for 12 months.
During the 12-month follow-up period, 74 patients (29%) were diagnosed with atrial fibrillation, of whom 93% were asymptomatic. Oral anticoagulation was recommended for all patients with atrial fibrillation, and at 12 months, 72 of 74 patients (97%) were receiving this treatment.
Over the course of follow-up, two strokes occurred in the atrial fibrillation group (both before the first episode of atrial fibrillation was detected and anticoagulation was initiated) and nine in patients without atrial fibrillation, however, the difference was not was statistically significant.
Three patients (1.2%) experienced complications with the device. One patient had an infection at the implantation site and the device had to be removed. One patient suffered a skin tear and the device had to be moved to another position. The third patient developed a subcutaneous hematoma (bruising).
Dr. Ratajczak-Tretel said, “In this study, we found that an implantable cardiac monitor was effective in diagnosing underlying atrial fibrillation, which was identified in 29% of patients with a stroke or TIA of undetermined cause. Once the probable cause of the stroke or TIA was detected, these patients were able to start oral anticoagulation. Atrial fibrillation was asymptomatic in most cases and may not have been detected or treated without ongoing monitoring.”
