Gender Differences of BMI & Waist Circumference as Atrial Fibrillation Risk Predictors

When we discuss cardiovascular disease, including atrial fibrillation or Afib, we often talk about risk factors to help us predict whether our patients need screenings and determine how soon we begin diagnostic testing. It may seem that with the many and varied causes of atrial fibrillation, including the fact that it can affect people of all ages and fitness levels, Afib is just one of those things you ultimately get and eventually treat. However, we know of certain factors that can help predict the risk of developing it. One such risk, and something that is unfortunately only getting worse in the United States and around the world, is excess weight and obesity. As a leading cause of longer-term cardiovascular issues like high blood pressure, atherosclerosis (or the narrowing of arteries due to plaque formation), type 2 diabetes, and sleep apnea, the excess weight represents a significant risk factor for developing and worsening Afib and other cardiac rhythm abnormalities.

An interesting 2021 study out of the Netherlands tried to understand the degree to which body fat distribution in the form of waist circumference and BMI or the body mass index might predict Afib development.¹ And does it matter if you’re a man or a woman?

More About the Study

This study is notable in part due to its breadth. The researchers dug up data on over 2,000,000 adults in the US and UK who did not have heart conditions. Of them, 12,000 had Afib. We already knew that a higher BMI and larger waist size were helpful in predicting Afib. Interestingly, however, the predictive value of these two factors was different for men and women, further highlighting that Afib treatment detection and treatment in women can be somewhat distinct than in men.

The correlation between BMI and Afib risk was more significant in women than between waist size and Afib risk. Adding BMI improved Afib prediction by 23% compared to only 12% using waist size. The opposite was true for men with waist size improving prediction of Afib by 30% while BMI improved Afib prediction by much less, at 23%.

While the differences between genders are fascinating, the bottom line is that this study highlights how we must always look to improve the detection and prediction tools we use. And sometimes it’s not advanced technology but simple anatomy that helps us learn more about the diseases we treat.

A Little More About the BMI

While the BMI is the best approximation of obesity today – it is a primary qualification factor for medical weight loss programs and even bariatric surgery – It is a somewhat archaic and incomplete measure. For one, it does not consider body type differences between genders. It also does not consider muscle tone or genetically larger frames. As such, you can imagine a bodybuilder would register as obese, yet they are far from it. Further, the cut-off numbers for overweight and obesity are purely arbitrary. We know this because some patients with higher BMIs have few obesity-related conditions while others with relatively lower BMIs may have significant metabolic concerns.

Yet, the predictive value of BMI related to Afib risk was precisely the same for men and women. It shows that, at least in this case, a standardized measurement like the BMI does have excellent predictive value.

Waist Size

Waist size is a somewhat different story. The difference between men and women was stark, showing that there’s a lot more we need to understand about fat (adipose) tissue that accumulates around the waist. From an Afib perspective, does abdominal fat affect women less than men, and do these results generally translate to cardiovascular disease? There’s a lot more that we need to learn. With that said, we know that fat around the abdomen is a predictor of heart disease for both men and women, and it’s why we always stress a healthier and improved lifestyle for patients that need it.

Next Steps

Those carrying excess weight can and should speak to their cardiologist and electrophysiologist like Dr. Tordini to learn more about managing their risk of follow-on cardiovascular disorders. It’s essential to take your heart health seriously, especially if you have risk factors for Afib and other cardiovascular diseases. These risks can be genetic or acquired, but regardless must be identified. With the prevalence of excess weight and obesity, understanding that your BMI as a woman and your BMI and waist size as a man can be highly predictive of Afib can help you seek the appropriate care.

And remember that Afib is not always obvious. The condition often starts as paroxysmal or occasional, and many dismiss this as a fluke. However, the episodes can become more persistent as time passes, increasing the risk of stroke, heart attack, and long-term heart failure. Afib can also be silent, with no outward symptoms. Further, a typical EKG performed during a primary care visit or even at your cardiologist’s office may not be enough to diagnose Afib. If you suspect that you have an irregular heartbeat, or if you are experiencing fatigue and your medical specialist has not been able to find the root cause, you may wish to consult with Dr. Tordini and discuss the possibility of paroxysmal or silent arrhythmia.

Reference:

1. Poorthuis MHF, Sherliker P, de Borst GJ, Carter JL, Lam KBH, Jones NR, Halliday A, Lewington S, Bulbulia R. Joint Associations Between Body Mass Index and Waist Circumference With Atrial Fibrillation in Men and Women. J Am Heart Assoc. 2021 Apr 20;10(8):e019025. doi: 10.1161/JAHA.120.019025. Epub 2021 Apr 15. PMID: 33853362; PMCID: PMC8174185.

Dr. Tordini is a part of Florida Medical Clinic Orlando Health