CXCR1 and atrial fibrillation: In contrast, we observed significant quadratic effects in FA for the left AF only: AF linear: F(1,76) = 3.87, p = 0.053, AF quadratic: F(1,76) = 7.77, p = 0.0067, ILF linear: F(1,76) = 8.85, p = 0.0039, ILF quadratic: F(1,76) = 3.20, p = 0.078, CC linear: F(1,76) = 0.31, p = 0.58, CC quadratic: F(1,76) = 2.047, p = 0.16.