Incidence and predictors of new-onset atrial fibrillation after cardiac surgery at Auckland City Hospital.

AIM

To describe the incidence, ethnic differences in incidence, and predictors of post-operative atrial fibrillation (POAF) after cardiac surgery in a New Zealand hospital.

METHOD

Analysis of registry data on 1,630 adults without previous atrial fibrillation having coronary artery bypass grafting and/or valve surgery was used to determine the incidence of POAF. Univariate analysis identified risk factors and stepwise logistic regression was used to create the most parsimonious model to predict POAF.

RESULTS

Overall POAF incidence was 29% (n=465) and differed by surgery type (25% after isolated coronary artery bypass surgery (CABG) vs 42% after combined CABG+valve). Incidence was highest in Māori (35%) and NZ/Other Europeans (32%). Māori and Pasifika with POAF were on average ten years younger than NZ/Other Europeans. Independent risk factors were age (OR 1.05, 95%CI 1.04-1.06), body mass index (OR 1.04, 95%CI 1.02-1.06), history of heart failure (OR 2.08, 95%CI 1.47-2.95), and valve surgeries (isolated valve OR 1.51, 95%CI 1.16-1.95; CABG+valve OR 1.59, 95%CI 1.11-2.28), but the model had poor discrimination (AUC 0.67).

CONCLUSION

POAF in a New Zealand hospital occurs at comparable rates to international settings. Risk models using routinely measured factors offer poor predictive accuracy, meaning risk stratification is unlikely to adequately inform targeted POAF prevention in clinical practice.