Big and Tall Young Men and Stout, Middle-Aged Men More Prone to AF

Marlene Busko

April 17, 2009

April 17, 2009 (Göteborg, Sweden) — Being big and tall as a youth or putting on a lot of weight in middle age puts men at higher risk of atrial fibrillation (AF) in older age, a new study reports [1].

Risk of AF was double for men in the highest quartile of body surface area (BSA) at age 20, and it was almost double for men in the highest quartile of weight gain from age 20 to midlife, after adjustment for body-mass index (BMI) and other factors.

The study, based on longitudinal data from men in the Swedish Primary Prevention Study who were middle-aged in the early 1970s, is published online March 20, 2009 in the European Heart Journal.

The researchers found an incidence of AF of 18% when the men were older. Strikingly, only 25 men (0.4%) were obese when they were age 20 during the period from 1935 to 1945, a time when obesity was rare in Sweden, the authors note.

"Given the current trends not only for obesity but also for height in many Western countries, we may be facing a substantial increase in the prevalence and incidence of AF in the future," the authors, led by Dr Annika Rosengren (Göteborg University, Sweden), caution.

Does Size Matter?

Obesity is a recognized risk factor for AF, partly because of the link between BMI and atrial volume, the researchers write.

To investigate the effect on AF from other measurements of body size--such as stature (height) and BSA--they analyzed data from men enrolled in the Swedish Primary Prevention Study. The men received interventions for hypercholesterolemia, severe hypertension, or heavy smoking.

The 6903 men had a mean age of 51.5 in the early 1970s, and, over a follow-up of to 34 years, 18.2% had a hospital discharge diagnosis of AF.

BSA was calculated based on midlife weight and recalled height at age 20. Weight change was calculated as the difference between midlife weight and recalled weight at age 20.

The risk of developing AF in later life increased linearly with increasing body size and with increasing midlife weight gain.

Obesity Growing Even in Sweden

"Overweight and obesity are less prevalent in Sweden than in many other European countries and in the US, but the current rate of increase is almost [as] high," the authors write.

They note that among middle-aged men in Sweden, those born in 1943 were 3 cm taller and almost 7 kg heavier than those born in 1913. This trend to taller, heavier youth, which is seen in several Western countries, suggests a significant impact on the future incidence of AF.

Looming Healthcare Crisis

Commenting on the study for heartwire , Dr Juan B Grau (University of Pennsylvania, Philadelphia) said it confirms the link between obesity and increased risk of AF that was seen in the Framingham cohort and in the Danish Cancer, Diet, and Health study.

The current study provides sound statistical analysis of a long prospective trial, but study limitations include an absence of data from women, use of a broad definition of AF, and a lack of structural data from echocardiograms, Grau said.

Nevertheless, the study provides good epidemiological data, and it does raise an important red flag about outcomes of the obesity epidemic, he said.

"This is the fourth big study that shows the same thing," he said. "We have one more data point showing that being heavy and [becoming heavy] over the course of a long period of time--in this case 20 years or more--is deleterious to your cardiovascular health. That's not breaking news. We know that."

This study provides insight into possible incidence of AF in the years to come. While the study found an incidence of AF of 18% in a population of Swedish men where obesity was only 0.4%, current obesity levels in the United States are far higher, as high as 40%, by Grau's estimate--although the Centers for Disease Control and Prevention (CDC) estimates are closer to 30%. "If these numbers [for the incidence of AF] are true, and I have no reason to doubt them, you are going to multiply these numbers by 40% in the coming two decades," Grau said.

No conflicts of interest were declared.

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