One interaction, between rs7164883 at the HCN4 locus and rs4980345 at the SLC28A1 locus, was found to be significantly associated with AF in the discovery cohorts (interaction OR = 1.44, 95% CI: 1.27-1.65, P = 4.3 × 10<sup>-8</sup>).
In conclusion HCN4-P883R may increase ectopic trigger and maintenance of AF by shifting the activation voltage of I<sub>f</sub> to more positive potentials and producing higher current density.