GOTEBORG, SWEDEN. Obesity as defined by a body mass index (BMI) exceeding 30 is now recognized as an important risk factor for the development of AF. BMI is calculated as the weight in kilograms divided by the square of the height in meters. A group of Swedish researchers now report that a large body size at age 20 years as well as weight gain from age 20 to mid-life are also significant risk factors for AF.

Their study involved 6903 Swedish men born in Goteborg between the years 1915 and 1925. During a follow-up spanning about 34 years, 1253 of the men (18.2%) were discharged from hospital with a diagnosis of AF. The researchers found that men with a large body surface area (BSA) at age 20 years had twice the risk of developing AF than did men with a BSA in the lowest quartile. BSA is defined as the square root of height measured in centimeters times weight in kilograms divided by 3600. A large gain (more than 35%) in weight between age 20 and mid-life increased risk by 61% when compared to a man whose weight had not changed between age 20 and mid-life. The data also confirmed that men with a mid-life BMI above 30 had twice the risk of developing AF as compared to those with a BMI between 20 and 22.5.

Finally, there was also a strong correlation between measured mid-life heights in men with a height greater than 179 cm (70.5 in) having a 68% increased risk when compared to those with a height below 172 cm (67.7 in). The researchers suggest that greater BMI, BSA and height are all associated with a larger left atrial size, which in itself has been associated with an increased incidence of AF. They conclude that, given current trends not only for obesity but also for height in many Western countries, we may be facing a substantial increase in the incidence and prevalence of AF in the future.

Rosengren, A, et al. Big men and atrial fibrillation: effects of body size and weight gain on risk of atrial fibrillation in men. European Heart Journal, Vol. 30, 2009, pp. 1113-20

Editor�s comment: It is interesting that our first LAF survey in February 2001 found that the average height for older male respondents was 183 cm (6 ft), 187 cm (6 ft 2 in) for younger men, and 168 cm (5 ft 6 in) for women. These numbers would put at least the men into the high-risk category for AF. The association between lone atrial fibrillation and tallness was confirmed in LAF Survey 11 as reported by Patrick Chambers, MD in his 2007 article �Lone atrial fibrillation: Pathologic or not?� published in Medical Hypotheses (2007; 68(2): 281-7).