What makes afibbers different?

KURASHIKI, JAPAN. The Kurashiki annual health survey is a prospective, population-based investigation aimed at determining incidence and risk factors for atrial fibrillation (AF) in men and women 40 years or older. The 2006 and 2007 surveys included 30,449 residents who underwent thorough medical examinations including 12-lead electrocardiograms. In the 2006 survey 439 participants were diagnosed with AF leaving 30,010 for follow-up to 2007. A total of 129 men (46.4%) and 149 women (53.6%) were diagnosed with AF at the 2007 survey giving an annual incidence of first diagnosed AF of 0.93%. The incidence increased markedly with age.

At or below the age of 67 years, the incidence was 0.53% for men and 0.15% for women, between 68 and 75 years, male incidence was 1.39% and female 0.65%, while at or over the age of 76 years, the incidence was 1.64% for men and 1.36% for women. In addition to age over 80 years, which was associated with a 57% increased risk of being diagnosed with AF, cardiac disease (coronary artery disease and heart failure) was a major risk factor associated with a 7.47 times increased risk.

Lower total cholesterol levels were also associated with increased risk as was a decreased glomerular filtration rate (a measure of kidney function). The Japanese investigators suggest that AF and deterioration of kidney function are linked through a common pathway of inflammation. The presence of hypertension and diabetes was not associated with an increased risk of AF and neither was smoking.

Iguchi, Y, et al. Annual incidence of atrial fibrillation and related factors in adults. American Journal of Cardiology, Vol. 106, 2010, pp. 1129-33

Editorís comment: The overall incidence of newly diagnosed AF of 0.93% a year in this cohort of Japanese citizens is very similar to that found in countries in the Western world. However, basing the presence or absence of AF on one, 12-lead electrocardiogram at rest would seem to me to be highly likely to underestimate the incidence since many cases of paroxysmal (intermittent) AF would likely be missed.