Breaking news: Heart monitors may prevent strokes

Heart monitors

One of the biggest challenges faced by stroke patients and their doctors is determining the cause of the stroke, so it can be prevented from happening again. Statistics show that up to 40% of stroke patients do not receive a clear diagnosis of what caused the stroke.

For many, this may be about to change.

Two studies published today on the New England Journal of Medicine have pointed out a way to root out one potential cause of stroke, making treatment possible for many patients.

Dr. Rod Passman, a professor of cardiology and preventive medicine at Northwestern University, is one of the scientists behind these new studies. Dr. Passman worked with 441 patients who had suffered a stroke of unknown causes. These patients were equipped with continuous heart monitors, which were used to study their heart behavior around the clock. This revealed the cause of stroke for about 30% of the patients: atrial fibrillation.

This is a major breakthrough in how these patients are treated to prevent their risk of a second stroke. "Finding atrial fibrillation, especially in someone who has already had a stroke, is vitally important," said Dr. Passman. "People with atrial fibrillation have a 500 percent increased chance of stroke, unless they receive proper treatment."

Atrial fibrillation is a heart condition in which the upper chambers of the heart contract irregularly and faster than usual due to an electrical disorder. The irregular movements of the heart cause blood to pool and clot, and these blood clots can cause a stroke if they find their way into the brain. Because of its irregular nature, atrial fibrillation is very hard to detect, as the heart may beat at a regular rhythm for any length of time without spasming. Says Dr. passman: "You may not know you have it, and when you come in with your stroke you could be in a normal rhythm. They could watch you for several days and never detect an abnormal rhythm."

For the clinical trials, half of the patients were fitted with an implanted heart monitor, which collected and transmitted heart data constantly. The rest of the patients were treated as is usual after a stroke: regular checkups and electrocardiograms. Results were compared at the end of the implanted monitor’s battery life (about 3 years), and while 30% of the patients with a monitor were diagnosed with atrial fibrillation, the condition was detected in only 3% of those who received standard post-stroke care. Dr. Passman pointed out the meaning of this discrepancy: "It wasn't that the patients receiving standard care weren't experiencing atrial fibrillation, it's that we weren't finding it."  

While this still leaves a large number of unexplained strokes still unexplained, finding a cause for 30% of them is a significant advance. These patients can now be treated with blood thinners and their risk of a second stroke significantly reduced, thanks to the prudent use of heart monitors.