An estimated 10.55 million American adults currently have atrial fibrillation, roughly 1 in 22 people. Globally, about 59 million people were living with AFib or a closely related irregular heart rhythm in 2023. Those numbers are climbing fast, driven by an aging population and rising rates of obesity and high blood pressure.
AFib in the United States
A 2024 analysis published by the National Heart, Lung, and Blood Institute put the U.S. figure at 10.55 million adults, or 4.48% of the adult population. That number is expected to reach 12.1 million by 2050, according to the CDC. The increase reflects both a genuinely growing problem and better detection: more people are being screened, and the tools for catching irregular rhythms have improved.
These official counts also miss a significant share of cases. An estimated 700,000 Americans have AFib without knowing it, about one in eight of all people with the condition. Among older adults specifically, nearly 14% of AFib cases are undiagnosed. More than half of these undiagnosed individuals have risk profiles that would typically call for blood-thinning medication to prevent stroke, meaning the gap in detection carries real consequences.
Global Numbers
Worldwide, AFib affected roughly 59 million people in 2023, with about 5 million new cases diagnosed that year alone. The condition is most common in North America, Europe, Australia, and Russia. While the heaviest burden falls on adults 65 and older, researchers tracking global data from 1990 to 2023 have flagged a growing challenge among younger and middle-aged adults as well.
How Age Changes the Numbers
AFib is overwhelmingly a condition of later life, and the prevalence curve is steep. Among primary care patients in a 2023 study, the breakdown by age tells the story clearly:
- Ages 65 to 69: 6.4%
- Ages 70 to 74: 10.3%
- Ages 75 to 79: 15.1%
- Ages 80 to 84: 22.4%
- Ages 85 and older: 28.5%
In practical terms, if you’re in your late 60s, roughly 1 in 16 of your peers has AFib. By your mid-80s, it’s closer to 1 in 3.5. This sharp rise with age is one reason population projections keep climbing as more people live longer.
Your Lifetime Risk
A large Danish population study found that the lifetime risk of developing AFib has risen from about 1 in 4 (in the early 2000s) to roughly 1 in 3 today. Starting from age 45, a person’s overall lifetime probability of being diagnosed with AFib is around 28%, and that figure has been trending upward over the past two decades. The increase isn’t entirely explained by aging populations. Rising rates of contributing conditions like obesity play a role too.
Differences by Sex
Men are diagnosed with AFib more often than women. In a study tracking over 25,000 middle-aged adults without prior heart disease over five years, 4% of men developed AFib compared to 3.2% of women. After adjusting for age and underlying health conditions, men still appeared to be at higher risk.
The picture gets more complicated when researchers account for body size differently. When height rather than BMI was used in the analysis, women actually appeared to have a higher risk. This suggests that standard statistical adjustments may undercount the true burden in women, and that AFib in women may be underrecognized.
Differences by Race and Ethnicity
AFib diagnosis rates vary significantly across racial and ethnic groups in the U.S., though the reasons are complex. In a large multi-ethnic study, white participants had the highest incidence rate. Compared to white participants after adjusting for age and sex:
- Hispanic participants had 51% lower incidence
- Chinese American participants had 40% lower incidence
- Black participants had 37% lower incidence
These gaps are real, but they likely reflect a mix of biological differences, unequal access to healthcare, and differences in how often people are screened. Lower diagnosis rates don’t necessarily mean lower true rates, particularly in communities with less access to cardiac monitoring.
What’s Driving the Increase
Two of the biggest modifiable risk factors are obesity and high blood pressure. Data from the Framingham Heart Study shows that obesity increases the risk of developing new AFib by 50%. For every 5-point increase in BMI (roughly the difference between a BMI of 25 and 30), AFib incidence rises by 30%. High blood pressure, which often accompanies excess weight, adds its own independent risk by putting chronic strain on the heart’s upper chambers.
The combination of longer life expectancy and rising obesity rates in most developed countries means the number of people living with AFib will continue to grow. Population aging alone would push numbers up, but the parallel increase in metabolic conditions is accelerating the trend beyond what demographics alone would predict.
The Role of Wearable Devices
Smartwatches and portable ECG monitors can now flag irregular heart rhythms, raising the question of whether consumer technology is meaningfully increasing detection. The evidence so far is mixed. A study comparing a portable single-lead ECG device to usual care found no overall difference in AFib diagnosis rates between the groups. The one exception was adults over 85, where the screening group had a higher detection rate (5.56% vs. 3.76%).
Wearables are better at catching AFib in people who already have it intermittently than at screening healthy populations. Large trials showing that wearable-driven detection actually prevents strokes or improves long-term outcomes haven’t been completed yet. Still, for older adults or those with symptoms like occasional palpitations, these devices can provide useful data to bring to a doctor.