Researchers from the University of Pennsylvania have found that people who are taller also have a higher risk of developing atrial fibrillation, a common heart condition, and that there may be a genetic link.

Atrial fibrillation is a condition characterized by an abnormal heartbeat—the heart may beat too fast, too slow, or the beats may be irregular.

According to the Centers for Disease Control and Prevention (CDC), around 2.7–6.1 million people in the United States have atrial fibrillation.

Though some people are unaware that they have it, due to a lack of obvious symptoms, atrial fibrillation can increase a person's risk of stroke.

Meanwhile, over 750,000 people end up in the hospital each year because of this heart problem, as per CDC data.

Recent research has shown that cases of atrial fibrillation have been on the rise, forecasting an "epidemic." But if people know that they are at risk of developing this condition, they can take steps to prevent it. They can also be better prepared to manage it, if it does develop.

Some recognized risk factors for atrial fibrillation include high blood pressure, obesity, diabetes, and heart disease, as well as some nonclinical factors, such as being older and being of European descent.

Now, a new study from Penn Medicine—a combined effort of the University of Pennsylvania Health System and the university's Perelman School of Medicine, in Philadelphia—suggests that being tall may be another risk factor for atrial fibrillation.

"Our findings suggest it may be beneficial to incorporate height into risk-prediction tools for [atrial fibrillation]," says lead study author Dr. Michael Levin.

He and colleagues will present their findings later this week at the American Heart Association's 2019 Scientific Sessions, in Philadelphia, PA.

Call to screen tall people for atrial fibrillation

The researchers report that for every 1-inch increase relative to average height—which they give as 5 feet and 7 inches, or approximately 1 meter and 70 centimeters—a person's risk of atrial fibrillation increases by approximately 3%.

However, this finding is not surprising, since past observational studies have also suggested an association between height and atrial fibrillation risk.

The issue that most interested the research team was whether there might be a causal relationship between height and atrial fibrillation risk.

To answer this question, the researchers analyzed genetic data from two large databases. One was that of the Genetic Investigation of Anthropometric Trials consortium. The investigators accessed this database to analyze the genes of 700,000 participants, looking for genetic variants associated with increased height.

The other was the database of the Atrial Fibrillation Genetics consortium, which allowed the researchers to analyze the genetic information of over 500,000 people, searching for genetic variants linked to a higher risk of atrial fibrillation.

Putting two and two together, the investigators found that many of the genetic variants associated with increased height were also linked to a higher risk of atrial fibrillation.

This relationship remained in place, even after the investigators adjusted for confounding factors, including heart disease, high blood pressure, and diabetes, which led the team to conclude that there may be a causal relationship between height and atrial fibrillation risk.

This notion was backed up by further analysis: When the researchers analyzed the data of an additional cohort of almost 7,000 participants enrolled in the Penn Medicine Biobank, they once more saw that a person's height, as well as genetic variants specifically associated with increased height, were strongly linked to an increased risk of atrial fibrillation.

Once again, these associations remained in place, even after the team adjusted for confounding factors, such as other known risk factors for atrial fibrillation.

These findings have led the study authors to suggest that, going forward, medical professionals may want to start including height on their list of important risk factors to consider in the context of heart health.

"While current guidelines advise against widespread screening for [atrial fibrillation], our findings show that a certain group of patients—specifically very tall patients—may benefit from screening."

Dr. Michael Levin

Senior author Dr. Scott Damrauer adds that "These analyses show how we can use human genetics to help us better understand causal risk factors for common disease."

"They also illustrate how we can combine summary-level statistics from large published studies with individual-level data from institutional biobanks to further our understanding of human disease," Dr. Damrauer explains.