Over 500,000 Americans have an ischemic stroke every year and the main cause of about one fourth of these cases is still unknown. This most common form of stroke blocks the flow of blood to the brain.
Two recent studies suggest that a common heartbeat irregularity often unrecognized called atrial fibrillation may be the cause of these strokes. Atrial fibrillation is a heartbeat disorder that's increasing among Canadians of older age. However, standard tests usually fail to detect the condition, leading to untreated patients prone to potentially fatal or disabling strokes.
"Atrial fibrillation can be notoriously difficult to diagnose because it is often silent and comes and goes intermittently, so it can be a hidden risk factor for stroke," Sunnybrook Health Sciences Center stroke prevention clinic director Dr. David Gladstone said. "Strokes related to atrial fibrillation are often devastating, causing long-term disability, dementia and death. They tend to be more severe and disabling and deadly than strokes due to other causes." Those who've had a stroke wear portable electrocardiograms for 24 hours to test irregular heartbeat episodes. However, the monitor often turns up with no anomalies so there can be no specific diagnosis.
It is vitally important to find atrial fibrillation especially in those who already suffered from a stroke. Those with the condition increase their chance of stroke by 500 percent unless proper treatment is given.
Two separate clinical trials were done to detect atrial fibrillation properly and see if heart monitors could resolve strokes from mystery causes. One trial was funded by heart device maker Medtronic and studied 441 patients who've had a stroke of unknown origin. Around 50 percent of the participants got an implanted heart rate monitor called Reveal ICM and a wand next to it transmitted heart data automatically over a phone to a cardiologist. The other 50 percent got standard care after a stroke which involved an electrocardiogram and regular doctor visits. The trial found that the monitor was 6.4 times better than standard care when it comes to atrial fibrillation detection at six months, 7.3 times more patients at 12 months and 8.8 times more at 36 months. After 36 months, 30 percent of the patients in the ICM group had the condition detected.
The other clinical trial assigned 50 percent of 572 patients randomly to a portable ECG device for about 30 days. The other half had their single heart monitoring in a laboratory for 24 hours. It was proven than the portable device was five times better at serious atrial fibrillation detection in stroke patients. The study found that atrial fibrillation was detected in around 20 percent of patients with the ECG device compared to only five percent of the control patients.
Better atrial fibrillation detection may lead to more patients receiving proper stroke prevention therapies, avoiding more strokes, disability, dementia and deaths.
