Familial Atrial Fibrillation Predicts Increased Risk of Mortality: A Study in Danish Twins

BACKGROUND: -Atrial fibrillation (AF) is a common arrhythmia. Several studies have shown association of genetic variants with AF, and that familial AF increases the risk of AF. We have previously shown a substantial heritability of AF in a twin study. The objective of this study was to determine whether having a co-twin with AF influences mortality. METHODS AND RESULTS: -We identified all Danish twins with AF born ≥ 1912 in the Danish Twin Registry, the National Patient Registry and the Central Office of Civil Registration. For each twin we randomly identified 4 twins without AF, matched on sex, zygosity and age. We compared survival among the co-twins of the affected twins (co-cases, n=2164) and the co-twins of the unaffected twins (co-controls, n=8626). The co-cases showed increased death rates compared to the co-controls (HR 1.20, 95% CI: 1.11-1.30, p