Gender distribution in lone atrial fibrillation

ROCHESTER, MINNESOTA. Our LAF surveys have consistently found a greater proportion of men (75-80%) than women among respondents. An early survey (August 2002) also suggested the possibility that lone atrial fibrillation may be an inherited disorder in many cases. The survey found that 43 of 100 respondents (43%) had at least one close relative with cardiac arrhythmia. The most common carrier was the mother who accounted for 30% of the relatives, siblings 26%, and fathers 23%. Permanent afibbers reported the mother to be the carrier in 71% of cases. Researchers at the Mayo Clinic now confirm that LAF is indeed more common among men and that there is a definite familial connection.

Their study included 192 unrelated lone afibbers who were divided into 3 groups. Group 1 consisted of 114 afibbers who had no relatives with atrial fibrillation (sporadic LAF), group 2 consisted of 44 afibbers who had 1 first- or second-degree relative with LAF (possibly familial LAF), and group 3 consisted of 34 afibbers who had 2 or more relatives with LAF (confirmed familial LAF). Thus, out of the total study population of 192 lone afibbers, 41% had a least one relative with LAF.

The proportion of men in groups 1, 2, and 3 were 82%, 84%, and 62% respectively. Sporadic LAF was more common among men (62%) than among women (51%). It was also clear that those with familial LAF (group 3) were more likely to have permanent afib (27%) than were those of groups 1 and 2 (8.2% and 6.8% respectively). As far as gender differences are concerned, the researchers observed that women afibbers were more likely to report palpitations and being awakened by palpitations at night than were men. Women were also more likely to have paroxysmal LAF (76% vs. 64% for men) and less likely to have persistent afib (11% vs. 25% for men).

The researchers conclude that the greater incidence of sporadic LAF among men would be partially due to x-linked recessive inheritance in which women, including the mother, may be asymptomatic carriers. They also conclude that sporadic and familial LAF are clinically indistinguishable.

Chen, LY, et al. Lone atrial fibrillation: influence of familial disease on gender predilection. Journal of Cardiovascular Electrophysiology, Vol. 19, August 2008, pp. 802-06

Editor’s comment: The Mayo Clinic study found that 41% of the 192 study participants had at least one first- or second-degree relative with LAF. This percentage is almost identical to the 43% observed in our August 2002 LAF survey. The male to female ratio of 79:21 found in the Mayo Clinic study is also very close to the 78:22 ratio found in our 2007ablation/maze survey. Comparing the above numbers gives a feeling of comfort that the findings reported in our surveys do indeed reflect the “real world”.