Lifetime risk of atrial fibrillation rises to nearly 31% in recent decade

By Dr. Liji Thomas, MDApr 17 2024Reviewed by Dr. Liji Thomas, MD

Atrial fibrillation (AF) is a common arrhythmia or cardiac rhythm disorder. It is associated with significant mortality risk and also a higher risk of multiple complications. As such, understanding the risk of AF in the population is necessary.

A new study published online in the BMJ explores the risk of both AF and its complications in a Danish national cohort, beginning from the age of 45 years. The results underline the risk for preventive strategies to reduce the burden of AF on public health. 

Study: Temporal trends in lifetime risks of atrial fibrillation and its complications between 2000 and 2022: Danish, nationwide, population based cohort study. Image Credit: Orawan Pattarawimonchai/Shutterstock.com

AF risk and complications

About 16 million and 18 million people are predicted to develop AF by 2050 in the USA and Europe, respectively. In this condition, the atria, or heart chambers that receive the venous blood, begin to show irregular twitches rather than a coordinated pumping contraction.

This prevents the efficient movement of blood through the atria into the ventricles, the main pumping chambers.

The complications of AF include stroke, heart failure, and heart attacks, though the overall and specific AF-related mortality risk has gone down over time. Primary and secondary prevention is, therefore, essential in protecting AF patients.

This motivated the present study, which seeks to establish the lifetime risk of AF in a large Danish cohort. Two periods were chosen to capture any change in risk over time.

Residual lifetime risk of a disease is the measure of the total risk that a given individual who does not have the disease at a specified age will develop it during the rest of the lifespan.

It helps educate the public about health risks and encourages compliance with healthy lifestyle recommendations. Not much is known about the long-term risk of several complications.

Though patients with AF are typically warned about their risk for stroke, all the long-term sequelae require more study, especially to identify how these risks have changed since the introduction of new stroke-prevention protocols for AF.

About the study cohort

The cohort included all Danes aged at least 45 years but less than 95 years who had never had an episode of AF. Those who developed AF from that point onwards were followed up for five complications arising from the diagnosis.

These included heart failure, any stroke, ischaemic stroke, myocardial infarction, and systemic embolism.

AF risk

There were over 3.5 million individuals without a history of AF at the age of 45 years or above. In this group, there was a rising prevalence of hypertension, diabetes, dyslipidemia, and stroke over the study periods among both the baseline population and those who developed AF after the study began.

AF was newly diagnosed in over 360,000 individuals with a similar age spectrum at the time of diagnosis in both periods. The lifetime risk of AF at 45 years was ~28% over the two decades of the study.

The same pattern was observed at the later index ages, viz., 55, 65, and 75 years. The risk at each age was 28%, 27%, and 24%, respectively.

Risk factors for AF included male sex, a history of hypertension, heart failure, heart attacks, other heart conditions, and dyslipidemia. Those with higher educational status and household income were also at greater risk.

Patients with stroke, chronic obstructive pulmonary disease (COPD), and chronic kidney disease (CKD) were more likely to die early compared to others, thus accounting for a significantly lower risk of AF over their lifespan.

Comparing the first decade to the second, they observed a 6.7% increased lifetime risk of AF from 45 years onwards, from 24% to 31%. This was unchanged after compensating for confounding factors. Similar increases were observed, by  6.5%, 6.3%, and 5.6%, at the later ages, respectively.

AF complications

The study shows a high lifetime risk of post-AF complications. While heart failure was the most common, affecting 41% of AF patients over their lifespan, stroke occurred in 21% of the patients. Heart attacks affected 12% of the patients.

Men had a higher risk, with 44% of them likely to develop AF complications, vs 35% of women with AF. The post-AF stroke risk was somewhat lower in men, affecting 21% of them vs 22.6% of women.

The risk of all AF complications except for all strokes was higher among hypertensive individuals.

Heart failure was much more likely among those who had a history of heart attacks, cardiomyopathy, or valvular heart disease, with the difference being as large as 22% to 45% compared to those without such conditions.

However, the lifetime risk of heart failure did not change over the study periods. Marginal decreases were observed in the risk of stroke (by 2.5%), ischemic stroke (~5%), and heart attacks (~4%).

When stratified by health condition, patients with hypertension or dyslipidemia had a reduced risk of post-AF heart failure over this period by 10% and 5%, respectively.

The heart attack risk among those with dyslipidemia went down by 11% vs 4% for those with normal lipid levels. These findings may be attributable to better medical care for such conditions. The risk of such complications decreases with age.

Conclusions

The study shows an increased lifetime risk for new AF over time, from one in four to one in three, over the two study periods. The most frequent complication was heart failure, affecting two out of five patients over the lifespan.

People with hypertension or dyslipidemia showed reduced lifetime risk of heart failure, however, compared with the general cohort, which showed no change in risk.

This is twice as high as the risk of post-AF stroke and four times greater than the risk of heart attack. This underlines the need for secondary prevention of heart failure in this group.

The results corroborate previous studies on the incidence of AF at various ages. The study demonstrates, for the first time, a rising risk of AF.

This may be due to better diagnostic methods and a lower threshold of suspicion, with improved clinical practice coupled with higher life expectancy. However, the increasing prevalence of risk factors like hypertension and diabetes must also be kept in mind.

By providing estimates of the lifetime risk of AF and its complications, the study could be important in helping to develop more efficient preventive strategies and policies.

For instance, stroke risk is managed by anticoagulants in Denmark, with compliance above 85%. The persistently high risk of stroke indicates the need for additional steps.

“As atrial fibrillation is a common arrhythmia, a lower incidence of complications may reduce the future economic costs in healthcare.”