TNNI3 and atrial fibrillation: 1) In patients with newly detected AF and concomitant HFpEF, one-fifth experienced MACCE during a median of 24 months of follow-up; 2) The elevated hs-cTnI group had a higher risk of MACCE, as driven by heart failure and revascularization-caused readmission; and 3) elevated hs-cTnI group and older age were significant predictors of MACCE in patients with newly detected AF and concomitant HFpEF.