NPPA and atrial fibrillation: However, atrial strain significantly modified the association between MR-proANP and AF (p for interaction = 0.009) such that MR-proANP was associated with AF in patients with high atrial strain [OR = 1.24 (1.06–1.46), p = 0.008, per 10% increase] but not in patients with low atrial strain.