A total of 429 patients were enrolled: 136 with AF (54 with lone AF), 84 with atrial flutter (36 [42%] of whom had a history of AF), 158 with SVT (14 [9%] of whom had at least one previous documented episode of AF), and 51 with no known arrhythmias. Baseline characteristics of those with and without a family history of AF for each group are shown in . Compared to the control groups (SVT and subjects with no known arrhythmias), the AF patients were generally older, more often white, and more often had a history of hypertension, coronary artery disease, and heart failure.
Baseline characteristics of subjects in each group.
A validation sample of first degree family members reported to have AF was contacted (family members of 5 lone AF subjects, 4 non-lone AF subjects, 2 SVT subjects, 1 atrial flutter subject, and 1 subject with no known arrhythmias), and 100% of the family members confirmed the diagnosis of AF.
Patients with AF more frequently had a first degree family member with AF (). The baseline characteristics of the AF subjects with and without a family history of AF are shown in . Of those with lone AF, 41% reported a first degree family member as having AF: in bivariate analysis, this proportion was significantly greater than the non-lone AF subjects and than all of the other subjects combined. Although approximately only one fourth of AF and atrial flutter subjects reported a family history of AF, each more commonly had a family history than did the control subjects. The atrial flutter patients with a previous history of AF more often had a first degree family member with AF than those without a prior history of AF (14% and 8%, respectively), but this was not statistically significantly (p=0.42). Lone atrial flutter patients (n=21) more often had a first degree relative with AF (19%) than the non-lone atrial flutter patients (8%), but this finding was not statistically significant (p=0.15).
Proportions of patients in each group that reported having at least one first degree family member with atrial fibrillation. P values represent comparisons denoted by brackets in bold.
Baseline characteristics of atrial fibrillation patients with and without a first degree relative with atrial fibrillation.
The ultimate diagnosis made during electrophysiology study in the SVT group resulted in a primary diagnosis of typical AV nodal reentrant tachycardia in 68 (43%), atrioventricular reciprocating tachycardia in 43 (26%), focal atrial tachycardia in 23 (15%), atypical AV nodal reentrant tachycardia in 6 (4%), reentrant atrial tachycardia in 1 (1%), junctional tachycardia in 1 (1%) and no inducible arrhythmia in 15 (10%, 2 with ventricular preexcitation). There was no difference in reported family history of AF between these groups, nor between those SVT patients with a history of AF and SVT subjects without a history of AF.
After logistic regression analysis adjusting for age, gender, race, hypertension, coronary artery disease, heart failure, and body mass index, those with AF had a 6 fold greater odds of reporting a first degree family member than the remainder of the subjects (95% confidence interval [CI] 2.93–12.7, p<0.001). Because, by definition, the lone AF patients did not have hypertension, coronary disease, or congestive heart failure, a separate logistic regression model was examined controlling for age, race, gender, and BMI (): after this adjustment, lone AF, non-lone AF, and atrial flutter patients each exhibited significantly greater odds of reporting a first degree family member with AF.
Odds ratios of having at least one first degree relative with AF in the lone AF, non-lone AF, and atrial flutter patients compared to controls after adjusting for age, race, gender, and body mass index. Error bars denote 95% confidence intervals.
Finally, after adjusting for these same potential confounders, lone AF patients had a 7 fold greater odds (95% CI 2.1–24.7, p=0.002) of reporting a first degree relative with AF than non-lone AF patients.
An attempt to re-contact the 49 subjects with a first degree family history of AF was made a mean 759 ± 295 days after the initial interview: 3 patients could not be contacted because they had moved out of the area and/or had changed phone numbers, 1 was deceased, and 13 declined to participate. Of the 31 that underwent a more detailed interview, 13 had lone AF, 8 had non-lone AF, 5 had AFL (1 with lone AFL), 3 had SVT, and 2 were normal controls. Three (23%) lone AF patients, 2 (25%) non-lone AF patients, and 1 (20%) AFL patient had 2 family members with AF. Only 2 subjects reported having 3 family members with AF: 1 with lone AF and 1 with lone AFL. The mean age at the first diagnosis of AF in the lone AF subjects was 59 ± 11 years old. Although not statistically significant, the mean age was older for the family members of the rest of the cohort (65 ± 11 years old, p=0.11) and for the family members of the non-lone AF subjects alone (68 ± 11 years old, p=0.074). The types of family members with AF are shown in ; of note, the total number of siblings, total number of children, and the total number of children over age 30 was not significantly different for those with lone AF versus the other groups. Although these findings did not reach statistical significance, of all subjects with at least one family member with AF who provided a detailed family history, the proportion of all family members with AF was greater for those with lone AF (25%) versus the remainder of the cohort (20%, p=0.52) and versus those with non-lone AF (19%, p=0.36); an analysis including only family members older than age 30 yielded similar results. Finally, only 2 subjects reported having 3 consecutive generations with AF, and both were lone AF subjects: a 47 year old white male with both parents and a son with AF and a 56 year old white male with a father and a son with AF.
Of the 31 subjects with complete family history data, the number of subjects with at least one family member of the type described in each row is shown.