Rich European countries have higher atrial fibrillation death rates than least wealthy

The researchers believe the difference between countries could be due to lifestyle factors, such as increased obesity and alcohol consumption in wealthier countries, or what is known as the 'survivor effect', where people live for longer due to better treatments for other diseases such as cancer, leaving greater numbers of more elderly people to die from diseases of the heart or circulatory system, such as atrial fibrillation.

Atrial fibrillation is a condition in which the heart beats at an abnormal and often rapid rhythm. It is one of the most commonly diagnosed heart rhythm disturbances and it can lead to stroke and heart failure. Until now, it's been unclear whether trends in deaths from atrial fibrillation vary between European countries and between men and women, and whether they have improved over time.

Professor Markus Sikkel, adjunct associate professor at the University of Victoria and clinical assistant professor at the University of British Columbia, Victoria, Canada, and Dr. Becker Al-Khayatt, a cardiology specialist registrar at Croydon Heart Centre, Croydon University Hospitals NHS Trust, London, UK, led a team of researchers to analyse data from the Global Burden of Disease Study on incidence and deaths from atrial fibrillation between 1990 and 2017 in 20 European countries [2]. They looked at trends over the 28-year period and calculated the mortality-to-incidence ratio (MIR) by dividing the numbers of deaths by the numbers of cases for each country. MIRs help to identify if a country has a higher or lower death rate per case diagnosed.

They found enormous variation between countries and there was no overall identifiable trend either towards or away from improved incidence and death rates, although the incidence of atrial fibrillation was consistently higher in men than in women in all countries throughout the study period.

Austria, Denmark and Sweden experienced peaks in incidence in the middle of the study period, while in nations with lower gross domestic product (GDP) there was less variability with a steady decline in incidence over the years, with a few exceptions. For example, in Portugal there was a sharp drop in incidence (-6% in men and -8% in women per year) between 2006-2009; in Italy there was a sharp rise in incidence in men between 1995-2001 (+3.5% per year); in Croatia incidence rates declined to the lowest levels in Europe in the first 10-20 years of the study (down to 39 per 100,000 men in 2000 and 24 per 100,000 women in 2006), but then rose sharply in men between 2006-2010 (+2.5% per year) and more slowly in women between 2010-2017 (+1.2% per year).

Death rates were highest in wealthier countries, reflecting the incidence in Austria, Denmark and Sweden. Sweden had the highest death rates for both men and women: 9 per 100,000 of the population in 2017, with a sharp 6% increase per year in male death rates between 2001-2006. In Sweden and Denmark, the mortality rates did not decline following the initial rise, unlike the incidence rates, and were among the highest in Europe by 2017. Germany also had a rapid and sustained increase in death rates throughout the 2000s, particularly in women, in whom they rose by 4% per year to 7 per 100,000 in 2017.

Mortality-to-incidence ratios stayed roughly the same for many countries over the 28 years, although increases occurred in Sweden, Germany and Denmark in both men and women. MIRs were consistently higher for women than men. The differences varied from relatively small in Bulgaria where the MIR was 5.4% higher in women than men in 2017, to large in Germany where the MIR in women was 74.5% higher than in men. In Austria the opposite occurred, with the disparity decreasing from 45.7% higher in women than men in 1990 to 19% higher in 2017.

Prof. Sikkel said: "The ratio of deaths to cases of atrial fibrillation in Europe has not improved over time and, in many European countries, it is actually increasing despite apparent advances in treatment and care. We think this could be due to differences in lifestyles in wealthier western European countries, where risk factors such as obesity, alcohol consumption and sedentary behaviour are more prevalent than in less wealthy, eastern European countries.

"The second important factor, in our view, is that patients in richer countries may survive long enough from other illnesses such as ischaemic heart disease and cancer, and then succumb to diseases that are more difficult to treat successfully: heart failure related to atrial fibrillation is one of these. Another possibility is that atrial fibrillation is less well recognised in poorer countries in a systematic way. We think this is likely to be a real difference and not just an artefact of better documentation in richer nations judging by the findings of previous studies."

Dr. Al-Khayatt said: "The gender disparity between men and women has persisted over many years in Europe and is rarely commented on. It is highly variable between nations and the cardiology community needs to work out why that is and whether different countries can learn from each other to reduce the disparity.

"We feel there are multiple factors behind this disparity, with healthcare inequality between men and women, as well as intrinsic biological differences being plausible explanations. There is some evidence that women are diagnosed later and treated less aggressively than men."

Limitations of the study include possible variations between countries in the data; data were not available for factors that could affect the results such as social class, obesity, smoking and alcohol use; atrial fibrillation and heart flutter were classified together although they carry different risks; and although there were differences between European countries in wealth, they are all still relatively wealthy compared to some other countries in the world.

In an accompanying editorial [3], Professors Michiel Rienstra and Isabelle Van Gelder, of the University Medical Center Groningen, The Netherlands, write: "The authors should be congratulated for their excellent contribution to our knowledge on the diversity of incidence of AF and AF-related mortality in Europe . . .it is interesting that both incidence and mortality are heterogeneous throughout Europe. This diversity may be explained by the fact that Europe is a non-homogeneous region."

They conclude: "This study emphasizes the diversity of incidence of AF and AF-related mortality throughout Europe. It underlines the differences in integrated AF care and access to it, and the clinical profile of AF patients in Europe. In addition, sex differences are emphasized. It is a call for more research in individual countries and more multinational studies including Western and Eastern European countries."

Notes:

[1] "Paradoxical impact of socioeconomic factors on outcome of atrial fibrillation in Europe: trends in incidence and mortality from atrial fibrillation," by Becker M. Al-Khayatt et al. European Heart Journal. doi:10.1093/eurheartj/ehaa1077

[2] The countries were: Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Netherlands, Poland, Portugal, Romania, Spain, Sweden, UK.

[3] "Incidence and outcome of atrial fibrillation: diversity throughout Europe," by Michiel Rienstra and Isabelle C. Van Gelder. European Heart Journal. doi:10.1093/eurheartj/ehaa1078