Heart failure, not stroke, is the most common complication of atrial fibrillation – which affects 37m people worldwide – say experts, calling for the profession to more comprehensively estimate the condition’s risk by considering multiple risk factors.
Atrial fibrillation increases not just risk of heart failure and stroke but also myocardial infarction and death, as well as quantifiable impairment in quality of life, write Jianhua Wu and Ramesh Nadarajah in The BMJ. They say that in the UK National Health Service (NHS) alone, more new cases of atrial fibrillation are diagnosed each year than the four most common causes of cancer combined, and direct expenditure on AF has reached £2.5bn.
They add that improvements to patient prognosis are likely to require a broader perspective on the condition’s management beyond prevention of stroke.
They write:
While the lifetime risk of the condition has been estimated, whether this has changed over the past two decades is unknown.
Furthermore, the comparative risks of later sequelae for individuals with atrial fibrillation, and whether trends are temporal, has yet to be reported.
A recent paper by Vinter and colleagues (in The BMJ) addresses these important knowledge gaps in a nationwide population-based study using the population of Denmark from 2000 to 2022.
The aim was to examine how the lifetime risks of atrial fibrillation and of complications after atrial fibrillation changed over time.
Using administrative registry data from 3.5m people, Vinter and colleagues estimate that the lifetime risk of AF for an individual 45 and older increased from 24.2% to 30.9% between the decades 2000-10 and 2011-22, a 28% relative increase.
This risk was larger in men than in women and in those with prevalent heart failure, myocardial infarction, stroke, diabetes and chronic kidney disease, compared with people who do not have these conditions.
Among patients with an incident diagnosis of AF, heart failure was the most frequent complication with a lifetime risk of 41.2%, double that of stroke (21.4%).
Comparing the two pre-specified periods, lifetime risk of heart failure after an atrial fibrillation diagnosis did not change, but absolute lifetime risks declined by 2.5% for stroke and by 3.9% for myocardial infarction.
Strengths of this observational study include the capture of data for a nationwide population of 3.5m individuals, and use of sophisticated methods (the Aalen-Johansen estimator) to accurately calculate the cumulative incidence of AF and complications while accounting for left truncation and the competing risk of death.
Limitations include the grouping of the population into two 10-year periods, resulting in the loss of temporal resolution; the lack of reporting on ethnic group composition of the study population, which influences lifetime risk of AF; and the absence of subgroup analysis by socio-economic status, which affects incidence and outcomes of atrial fibrillation.
Their conclusion was that lifetime risk of atrial fibrillation increased over two decades of follow-up. In individuals with AF, about two in five developed heart failure and one in five had a stroke over their remaining lifetime after atrial fibrillation diagnosis, with no or only small improvement over time.
Stroke risks and heart failure prevention strategies are needed for people with atrial fibrillation, they said.
Unsurprising
The finding that lifetime risk of atrial fibrillation has increased over the past two decades is not surprising because many other studies have shown increasing atrial fibrillation incidence.
Nonetheless, routinely collected data show that contemporary lifetime risk of AF has increased to one in three because up to 35% of disease burden remains undiagnosed.
By contrast, the incidence of myocardial infarction has decreased over recent decades, in association with national programmes of vascular checks to address key risk factors for ischaemic heart disease.
This new study reinforces the principle that analogous primary prevention programmes for atrial fibrillation are required to stem the apparent rise in incidence, associated disease burden, and cost.
Unfortunately, the evidence base for primary prevention of AF predominantly relies on observational data and post-hoc analyses of data from randomised clinical trials where atrial fibrillation was not pre-specified as a primary or secondary endpoint, and occurrence was not systematically collected.
As a consequence, international guidelines do not provide specific recommendations for interventions to reduce the risk of newly onset atrial fibrillation.
While difficulties in identifying a group at sufficiently high risk for AF historically impeded primary prevention trials, opportunities are now available to comprehensively estimate risk by considering multiple risk factors.
As such, Vinter and colleagues’ findings should act as a call to prioritise prospective trials in this area.
The analysis is also noteworthy for quantifying long-term risks of sequelae after an atrial fibrillation diagnosis. AF care has improved considerably in recent decades, informed by randomised clinical trials showing that oral anticoagulation, and more recently, catheter ablation, reduce the risk of stroke and death.
These interventions are being increasingly used worldwide.
International guidelines emphasise stroke prophylaxis in patients with atrial fibrillation; yet, Vinter and colleagues’ analysis shows that the lifetime risk of heart failure outweighs the risk of stroke.
The neglect of heart failure as a complication of AF in international guidelines is conspicuous because, similar to stroke, heart failure is associated with functional limitations, decreased quality of life, and poor prognosis, and the subpopulation who have both atrial fibrillation and heart failure have a significantly increased risk of cardiovascular and all-cause mortality.
Prospective cohort studies have established factors identifying people at high risk of heart failure after an AF diagnosis. However, whether more intensive interventions directed towards modifiable cardiovascular risk factors could affect their long term incidence of heart failure has not been prospectively tested, and requires further investigation.
Interventions to prevent stroke have dominated AF research and guidelines during the study period in Vinter and colleagues’ analysis, but no evidence suggests that these interventions can prevent incident heart failure.
Alignment of both randomised clinical trials and guidelines to better reflect the needs of the real-world population with AF is necessary because further improvements to patient prognosis are likely to require a broader perspective on the condition’s management beyond prevention of stroke.
This robust observational research by Vinter and colleagues provides novel information that challenges research priorities and guideline design, and raises critical questions for the research and clinical communities about how the growing burden of atrial fibrillation can be stopped.
Study details
Temporal trends in lifetime risks of atrial fibrillation and its complications between 2000 and 2022: Danish, nationwide, population based cohort study
Nicklas Vinter, Pia Cordsen, Ludovic Trinquart et al.
Published in The BMJ on 17 April 2024
Abstract
Objectives
To examine how the lifetime risks of atrial fibrillation and of complications after atrial fibrillation changed over time.
Design
Danish, nationwide, population based cohort study.
Setting
Population of Denmark from 1 January 2000 to 31 December 2022.
Participants
A total of 3.5 million individuals (51.7% women and 48.3% men) who did not have atrial fibrillation at 45 years of age or older were followed up until incident atrial fibrillation, migration, death, or end of follow-up, whichever came first. All 362 721 individuals with incident atrial fibrillation (46.4% women and 53.6% men), but with no prevalent complication, were further followed up until incident heart failure, stroke, or myocardial infarction.
Main outcome measures
Lifetime risk of atrial fibrillation and lifetime risks of complications after atrial fibrillation over two pre-specified periods (2000-10 v 2011-22).
Results
The lifetime risk of atrial fibrillation increased from 24.2% in 2000-10 to 30.9% in 2011-22 (difference 6.7% (95% confidence interval 6.5% to 6.8%)). After atrial fibrillation, the most frequent complication was heart failure with a lifetime risk of 42.9% in 2000-10 and 42.1% in 2011-22 (−0.8% (−3.8% to 2.2%)). Individuals with atrial fibrillation lost 14.4 years with no heart failure. The lifetime risks of stroke and of myocardial infarction after atrial fibrillation decreased slightly between the two periods, from 22.4% to 19.9% for stroke (−2.5% (−4.2% to −0.7%)) and from 13.7% to 9.8% for myocardial infarction (−3.9% (−5.3% to −2.4%). No evidence was reported of a differential decrease between men and women.
Conclusion
Lifetime risk of atrial fibrillation increased over two decades of follow-up. In individuals with atrial fibrillation, about two in five developed heart failure and one in five had a stroke over their remaining lifetime after atrial fibrillation diagnosis, with no or only small improvement over time. Stroke risks and heart failure prevention strategies are needed for people with atrial fibrillation.
The BMJ article – The growing burden of atrial fibrillation and its consequences (Open access)
See more from MedicalBrief archives:
Simple procedure slashes atrial fibrillation risk following cardiac surgery
Rethinking AF treatment to prevent life-threatening conditions – Canadian studies
Simple procedure slashes atrial fibrillation risk following cardiac surgery