Where Are the Biggest Risks in the U.S. for Atrial Fibrillation Hospitalizations and Strokes
June 3, 2010 6:21 AM CT
By Peggy Noonan and Mellanie True Hills
One of the most puzzling things about atrial fibrillation is geography and how a person’s location affects his or her risk of atrial fibrillation and stroke.
This February, the Centers for Disease Control and Prevention (CDC) published a map as part of its Atrial Fibrillation Fact Sheet that dramatically illustrates which parts of the country have the highest rates of hospitalizations for atrial fibrillation. The map was based on data from people on Medicare who were 65 or older and were hospitalized for atrial fibrillation between 2000 and 2006.
Trends in Atrial Fibrillation Hospitalizations
The highest rates of Medicare atrial fibrillation hospitalizations, as shown on the map in dark red, are in:
- The southeastern coastal plains
- Central Maine
- Chicago (metropolitan area)
- St. Louis (greater St. Louis region)
The interesting thing about that is that even though atrial fibrillation frequently results in strokes, these hotspots don’t exactly match the areas known as the nation’s “Stroke Belt”, the eight southeastern states that have high stroke rates—Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee—and its three “Stroke Buckle” states, North Carolina, South Carolina and Georgia.
On the CDC map, the really high levels of atrial fibrillation begin in the Appalachian foothills of Northern Alabama, starting around Birmingham, and range all the way up to Western Pennsylvania, to Pittsburgh and beyond. From there, they move eastward to Pennsylvania’s Allentown-Bethlehem area and westward to Cleveland, Ohio.
Could that point to an environmental connection, such as a link to coal mines and steel mills or other heavy industry? The fact that there’s also a high concentration around another former major steel industry center just outside Chicago, near Gary, Indiana, seems to support that theory. There’s also a high concentration clustered around the Gulf Coast in the Florida panhandle, south Alabama and Mississippi, and although there’s no steel-making industry in that area, there are many retirees from steel-producing regions.
The Stroke Buckle Paradox
The real paradox in this map is that the concentration of atrial fibrillation hospitalizations in the three Stroke Buckle states—Georgia, South Carolina, and North Carolina—doesn’t appear as high as the other Stroke Belt states even though we’ve known for decades that stroke death rates are higher there than in other parts of the country.
The reason for the higher level of deaths in Stroke Buckle states remains a mystery say the authors of a 2008 study published in the journal Neuroepidemiology, by Ilan Shrira, Ph.D. (Department of Psychology at the University of Florida, Gainesville), Nicholas Christenfeld, Ph.D. (Department of Psychology at the University of California, San Diego), and George Howard, Dr.PH. (Department of Biostatistics at the University of Alabama School of Public Health).
For their study, they examined all death records in the US between 1979 and 1988 and noted what county people had lived in and whether they died inside or outside the Stroke Buckle. Analyzing the data showed the risk of dying of stroke was higher both in people who lived in the Buckle and in people who visited the Buckle. And, people who lived in the Buckle but died elsewhere were less likely to die from stroke.
Something about the Buckle itself seems to be the culprit.
Many explanations for the Stroke Belt and Stroke Buckle have been proposed, including poorer health care in the region, infectious agents (infections have been found in one-fourth to one-third of stroke victims prior to death), genetic predispositions, and environmental toxins in the water or soil, but while some may play a role, none of the explanations accounted for the increased deaths and the cause remains a mystery.
“Our goal here was to show that even short-term exposure to the Stroke Buckle plays a role in this continuing epidemic,” the authors conclude. Although they note that there wasn’t enough data available on factors such as how long visitors were in the area or whether the reason for their visit might have some bearing on their stroke risk to identify whatever it is that increases stroke risk in the Buckle, they hope their findings will encourage other researchers to explore this further.
The CDC map and the Stroke Buckle study are fascinating and thought-provoking.
At this point, we have more questions than answers. Having grown up in Alabama, and having also lived in Georgia and the Florida panhandle—all areas where high humidity results in mold issues—I’d like to see the role of molds and inflammation explored as it relates to atrial fibrillation and strokes.
Molds and other environmental allergies have always been a huge issue for me, causing frequent sinus infections while I grew up in Birmingham and also while away at college in Auburn, Alabama. No matter where I’ve lived, when it gets humid and moldy, whether coastal or inland, I get sinus infections. We know there is a relationship between inflammation and atrial fibrillation, as well as other heart issues, so could the preponderance of molds in humid climates, such as the southeastern stroke belt states, play a role? Are there more hospitalizations during the spring and fall when the molds are at their worst? I haven’t seen data by time of year, but would love to.
Of course, having grown up in the shadow of the steel mills in Birmingham, and having breathed in those pollutants, could also have been a factor in the inflammation, which was then simply exacerbated by the molds. We talk about strokes running in families in the south. We also know that atrial fibrillation runs in families. Is it always genetic? While genetic components of atrial fibrillation have been identified in certain populations, could an environmental factor shared by whole families be more responsible than genetics in the south and other parts of the country?
There could be some credence to molds being an issue in that there is also a concentration of afib hospitalizations along the Gulf of Mexico and Florida Atlantic coastal areas, which are frequently ravaged by hurricanes and coastal flooding that leads to severe mold issues. There is also a prevalence throughout the Ohio River Valley, Louisiana, eastern Texas, and even the Red River Valley along the Texas-Oklahoma border, an area highly subject to flooding. Another possible contributor in some of those areas might be the presence of oil refineries, or even oil or gas drilling. That could also be an influencer in Pennsylvania and maybe New Jersey as well.
As a “data-junkie”, I find these maps fascinating and would love to get your feedback as to whether the environment in which you were raised and where you live now could be influencers of your current afib. There have to be reasons why some areas have much higher afib hospitalizations than others, and I’d love your thoughts based on what you see in this data. Please share your thoughts at our forum, where I’ve started a thread on this topic: Why Is Atrial Fibrillation More Prevalent in Some Regions Than In Others?
To learn more, see:
- Atrial Fibrillation Hospitalization Map and Atrial Fibrillation Fact Sheet, February 2010, Centers for Disease Control and Prevention (CDC)
- Visiting the South’s ‘stroke buckle’ increases risk of stroke death, University of Florida News, June 5, 2008
- Exposure to the US Stroke Buckle as a Risk Factor for Cerebrovascular Mortality, Neuroepidemiology, published online April 25, 2008
From the CDC Atrial Fibrillation Fact Sheet:
- The two most common complications of atrial fibrillation are stroke and heart failure.
- Atrial fibrillation is responsible for between 15 and 20 percent of ischemic strokes. Ischemic strokes are the kind caused by blood clots or plaque (fatty deposits from the lining of blood vessels).
- The risk of ischemic stroke is 5 times higher in people who have atrial fibrillation.
- The mortality rate from atrial fibrillation, whether it’s the primary cause or an underlying cause of death, has been rising for more than 20 years.
- An estimated 2.66 million people will have atrial fibrillation this year (2010) and that number will more than quadruple to as many as 12 million by 2050.
Peggy Noonan specializes in writing about health for consumers and medical professionals. She writes for leading national magazines and consumer publications as well as StopAfib.org.
Mellanie True Hills is founder and CEO of StopAfib.org and an atrial fibrillation survivor.