De novo atrial fibrillation after mitral valve surgery.

Objectives: We sought to determine the incidence and risk factors for de novo atrial fibrillation (>90 days after surgery) in patients without preoperative atrial fibrillation.

Methods: From 2004 to 2014, 2261 patients underwent mitral valve surgery; 1288 patients (57%) did not have a history of atrial fibrillation, and 930 patients had rhythm information more than 90 days after surgery. De novo atrial fibrillation and death probabilities were estimated using a semi-competing risks, multi-state model. Univariable and multivariable risk factors for developing atrial fibrillation were identified using the Fine-Gray model.

Results: The 5- and 10-year incidences of de novo atrial fibrillation were 14% and 23%, respectively. Univariable risk factors were older age, more complex operations, more tricuspid regurgitation, and congestive heart failure (all P < .05). Patients with degenerative mitral regurgitation were less likely to develop atrial fibrillation (hazard ratio [HR], 0.4; 95% confidence interval [CI], 0.24-0.65; P < .001). Multivariable risk factors for de novo atrial fibrillation were tricuspid valve surgery (HR, 1.80; 95% CI, 1.22, 2.65; P = .003), aortic valve surgery (HR, 1.49; 95% CI, 1.03-2.17; P = .035), and older age (HR, 1.03; 95% CI, 1.02-1.05; P < .001). De novo atrial fibrillation did not affect overall survival (P = .41). Among patients who developed de novo atrial fibrillation, we observed increased use of warfarin (P < .001) and a strong trend toward an increased risk of stroke (P = .055).

Conclusions: De novo atrial fibrillation develops progressively after mitral surgery and is associated with a strong trend toward stroke. Patients at high risk could be studied in a trial to reduce atrial fibrillation.