These findings should lead healthcare providers to be on the lookout for signs of atrial fibrillation in their patients who have persistent asthma, says Nazem Akoum, MD, the director of the atrial fibrillation program and an associate professor of medicine at the UW School of Medicine in Seattle. Dr. Akoum was not involved in the study. Although there are no immediate changes in screenings or guidelines around asthma and afib, this relationship will be something providers consider in patients with asthma, according to Akoum. “We’re going to be looking for this much more carefully in that group,” says Akoum. A diagnosis of atrial fibrillation indicates that someone is at increased risk for heart failure and stroke, too, he adds. This data isn’t the first to suggest that asthma may increase afib risk. But, significantly, this study is one of the first to look at such a large, diverse sample in the United States, explains Matthew Tattersall, DO, an assistant professor of cardiovascular medicine at the University of Wisconsin in Madison and the lead author of the research. In the retrospective analysis, published online earlier this month in Circulation: Arrhythmia and Electrophysiology, investigators used data from 6,615 individuals in the Multi-Ethnic Study of Atherosclerosis (MESA) cohort. No one in the group had heart disease at the start of the study; 150 people had persistent asthma (defined as disease severe enough to require daily controller medications); and 497 people had intermittent asthma (defined as disease that caused bouts of shortness of breath and coughing but didn’t require those individuals to have to take a daily medication to control their asthma). The authors hypothesized that underlying common inflammatory processes in asthma and afib might make the latter more common among people with asthma, Dr. Tattersall says. The participants in the group represented a diverse sample. The average age of the participants was 62; 53 percent were women; 27 percent were African American; 22 percent were Hispanic; and 12 percent were Chinese. Investigators followed the participants for an average of 12.9 years and used electrocardiogram results, hospital discharge diagnoses, and Medicare claims data to determine if someone developed atrial fibrillation. After controlling for several factors including smoking status, alcohol consumption, education level, blood pressure, and the presence of diabetes or sleep apnea, the analysis revealed that the incidence of afib was about the same for people without asthma and for people with intermittent asthma — about 11 cases per 1,000 persons per year. But in the group with people with more persistent asthma, there were 19 cases per 1,000 persons per year, representing a nearly 1.5 times increased risk.

The Study Adds to Growing Evidence That Respiratory Problems Are Linked to Afib, and the Data Is Unique Because of Its Diversity

Prior studies looking at the association between atrial fibrillation and asthma were done in Japan, Norway, and England, Tattersall notes. They were population studies that were able to include a large number of people, but they didn’t have the diverse population included in this research, he explains. RELATED: Asthma Complications You Might Run Into Now and Later “Those studies also didn’t have access to the kind of granular detail that we have in MESA; we have access to lab work and imaging for the subjects. We were able to look at a lot of different features that may contribute to the development of atrial fibrillation, as well as adjust for a lot of different factors that other studies weren’t even able to look at,” says Tattersall. Both these features add to the strength of the study, he says. The diverse sample helps show that this effect isn’t just happening in people of one race or ethnicity, Akoum says. “That’s very important.” The data suggests more research is needed to understand whether specific races or genders are more affected than others. “Looking at gender differentials deserves more attention,” Tattersall says. “We observed a trend that suggests that women with asthma in particular seem to have a higher risk for afib compared with women without asthma. It would be interesting to see if that trend was present in larger studies,” he says.

The new study showed an association between persistent asthma and developing atrial fibrillation, but the findings also raise some additional questions about that relationship. Because the researchers had access to participants’ blood samples in this study, the researchers could study potential mediators of this relationship between asthma and heart arrythmia, says Akoum. “They actually looked at inflammatory biomarkers from the blood and showed that this relationship between persistent asthma and atrial fibrillation was not explained by these inflammatory biomarkers,” he says. The bottom line is, the data suggests there’s a correlation between the two conditions, but it doesn’t show not what’s causing that correlation, Akoum says. “Further investigation is needed to understand the steps that lead us from a respiratory problem to a cardiac problem, but we do know from these results that it can’t all be explained by inflammation,” says Akoum. The other question that needs further study is whether controlling asthma through treatment will reduce the risk of atrial fibrillation and all its potential consequences, like heart failure and stroke, says Akoum. “That piece is not proven,” he says. Further research is also needed to unravel the different risks associated with the different types of asthma. For example, is there a specific type of asthma that is at higher atrial fibrillation risk? says Tattersall. “We know that grouping asthma as a singular entity is probably not the best way to think about the condition,” says Tattersall. “There are specific forms of asthma and each are treated a little bit differently,” he says. RELATED: A Guide to Asthma Treatment

So, What Can You Do if You Currently Have Asthma?

Patients with more severe forms of asthma should be aware that there is an increased risk for atrial fibrillation, and that they should talk with their doctor about how diet and exercise might help minimize that risk, says Tattersall. There has been a lot of data that has come out that suggests there are modifiable risk factors in developing atrial fibrillation, according to Tattersall. “One of the largest modifiable risk factors that can make the biggest difference was exercise and weight loss,” he says. Tattersall references the ARREST AF Cohort Study, published in December 2014 in the Journal of the American College of Cardiology (JACC), and another trial known as the LEGACY study, published in May 2015 in JACC. In both those studies, people who lost weight and exercised actually improved their atrial fibrillation, notes Tattersall. “Combined with that, we know that in certain forms of asthma, maintaining an ideal body weight can also help improve symptoms,” he says. According to the American Lung Association, extra weight increases the risk of asthma and of more severe asthma that’s harder to control with medication. RELATED: Your Everyday Guide to Living Well With Asthma