Postoperative atrial fibrillation: function over fibrosis, prevention needed
Y Zhang, H Wang, D BendittAbstract
Background
Postoperative atrial fibrillation (POAF) is a frequent complication after cardiac surgery, associated with increased risks of stroke, heart failure, and mortality. Although preventive strategies have been explored, the mechanisms underlying POAF remain uncertain. Clarifying whether POAF results from irreversible atrial fibrosis or transient autonomic dysfunction may help refine both its prevention and clinical interpretation.
Methods
In this prospective observational study, we evaluated both structural and functional determinants of POAF. A total of 4030 participants were enrolled, including 16 healthy volunteers and 4014 patients scheduled for cardiac surgery. Among them, 16 volunteers and 85 patients underwent 18F-AlF-FAPI–PET-MRI to quantify atrial fibrosis, with 22 valvular AF patients serving as positive controls. An additional 3929 surgical patients without preoperative AF (556 with valvular disease and 3373 with coronary artery disease) underwent perioperative heart-rate-variability (HRV) analysis to assess autonomic function. Continuous electrocardiography and 7-day Holter monitoring were used to detect POAF.
Results
Patients with cardiovascular disease exhibited significantly higher atrial fibrosis than healthy controls (P<0.01), but fibrosis burden did not differ between those with and without POAF (P>0.05). In contrast, HRV indices were consistently higher in POAF patients than in non-POAF patients (P<0.001), and all parameters (HF, LF, SDNN, rMSSD, and pNN50) increased progressively within 10–20 minutes before POAF onset. These changes reflected simultaneous sympathetic and parasympathetic activation without alteration in LF/HF ratio, indicating transient autonomic co-activation rather than fixed structural remodeling.
Conclusions
POAF arises not from irreversible atrial fibrosis but from transient autonomic disequilibrium superimposed on a structurally vulnerable atrium. Early prevention targeting autonomic stabilization represents a rational and necessary strategy to restore physiologic balance before dysfunction becomes disease.Fibrosis Burden in different locationsHRV indices before POAF onset