That's because patients with a high stroke risk due to heart rhythm problems are likely to turn up at the ER for symptoms of their irregular heartbeat, giving doctors a chance to make sure they're on the best drugs to prevent a stroke.
The study's results show that ER patients on the whole are 20 percent more likely than the general population to have the heart rhythm irregularity called atrial fibrillation, which significantly raises the risk of stroke.
But only 55 percent of the AF patients seen in the ER who could be taking the best available medication to prevent strokes actually are taking that drug. The study's authors say the ER could be a good place to identify AF patients who aren't getting the best preventive therapy they can get, and to help steer them to better treatment.
The study, published in the November issue of Stroke, was conducted at three hospitals, and led by a researcher from the University of Michigan Health System.
"The scope of the problem is extraordinarily large," says lead author Phillip A. Scott, M.D., an assistant professor of emergency medicine at UMHS and member of the UMHS Stroke Program. "The ER is potentially an efficient place to identify untreated and under-treated atrial fibrillation patients, to inform them of their stroke risk, and to treat them or refer them for treatment."
AF can cause blood to pool and clot in the heart's upper chambers, leading to a stroke when clots leave the heart and travel to the brain. About 15 percent of the nation's strokes occur among the 2 million Americans with AF, who often have other cardiovascular diseases like clogged arteries, high blood pressure, or heart failure.
The idea of using ER visits for preventive care is a relatively new one, Scott says, but research at UMHS and elsewhere has shown that such visits can be "teachable moments" for patients. Prevention messages seem to sink in well immediately after a health crisis, Scott explains, motivating patients to change their ways.
The new results suggest that AF patients may be a perfect population to target for preventive messages in the ER. The study is the first to document an elevated rate of AF among ER visitors -- 1.1 percent of all ER patients, as opposed to the estimated 0.89 percent of the total American population.
And, the findings show that many people with atrial fibrillation are still getting no treatment or sub-optimal treatment to prevent clots and stave off a stroke.
A blood thinning drug called warfarin, often sold as Coumadin, is the gold-standard stroke prevention drug for most patients with AF. Some who cannot take warfarin because of other conditions are given a prescription for anti-platelet drugs or aspirin. But the new study, like other recent studies, shows that only about half of AF patients eligible for warfarin therapy are taking it.
"Current computer models estimate that we could prevent 40,000 strokes each year if we were able to get all eligible patients on appropriate medication," says Scott. That number is based on data showing that anticoagulation therapy in AF patients decreases the risk of strokes caused by clots by 68 percent, while only increasing strokes caused by bleeding by 0.3 percent.
Even as warfarin use lags, emergency room visits are climbing. More than 30 percent of all ER visits are made by people over 45 years of age, the key at-risk population for AF. And AF is the most common heart rhythm disorder seen in ER patients; AF patients are likely to visit the ER for chest pain, shortness of breath and heart palpitations. In addition, the ER is an important source of health care for people without health insurance or a regular health care provider.
The new study looked at adult patients who had an episode of active AF diagnosed by electro-cardiogram (EKG) in a six-month period in one of three emergency departments in tertiary-care hospitals: UMHS, St. Joseph Mercy Hospital in Ann Arbor, MI, and University of Cincinnati Hospital.
Working from medical records and a database of EKG records, the researchers identified 78,787 emergency patient visits, and 15,238 EKG results. Of those who had EKGs, 871 had AF, and full records were available for 866 of them. This gave the overall AF incidence rate of 1.1 percent.
Patients who had no previous AF diagnosis, or whose AF involved a heart valve, were not included in an analysis of medication patterns. A total of 478 individual patients with recurrent non-valvular AF, 63 of whom had more than one ER visit in the study period, were identified.
The mean age of the 478 patients was 74.5 years, meaning that many of the patients were at an increased risk of stroke not only from their AF but also from their age. Just over one-quarter of the patients had three high-risk factors for stroke.
Warfarin isn't for everyone, so Scott and his colleagues used strict standard guidelines to determine who was eligible for the drug and who wasn't, including those who had bleeding and liver problems, a history of falls or problems walking, or uncontrolled high blood pressure. A total of 240 patients weren't eligible for warfarin under these guidelines, and even some of the patients who were found to be on warfarin would have been ineligible under the guidelines.
Of the 291 patients who were eligible for warfarin, only 55 percent were on the drug. Another 22 percent were using antiplatelet drugs that can help slow clotting. But 23 percent were getting no stroke-prevention therapy at all. And of those who weren't eligible for warfarin but could take antiplatelet or aspirin therapy, only 34 percent were using any of the drugs.
The study also looked at the results of blood-clotting tests called INRs, to see if patients' therapies were having the desired effect. "In this study, effective anti-coagulation treatment was the exception, not the rule," says Scott. "Only one-third of those tested were within guidelines."
Though the authors don't think that ER doctors should try to manage stroke-prevention therapy for AF patients on their own, they do believe that the ER can play a big role in helping find patients who could benefit from available therapies. This includes increased use of EKG and INR blood tests.
"We need a multilevel approach to decrease the death and disability caused by stroke," says Scott. "The ER is a logical component of this approach. This study is just the first step in evaluating the ER as a part of stroke prevention efforts, but we hope further studies will be conducted."