TET2 and atrial fibrillation: Multivariable Cox regression showed that TET2 mutation (p = 0.042, HR = 4.361, 95% CI 1.053–18.056) and increased IL‐1β (p = 0.012, HR = 5.476, 95% CI 1.547–28.123) were significant risk factors for AF in patients with JAK2V617F‐positive MPN.