A Clinical Prediction Model for Postcardiac Surgery Atrial Fibrillation in an Asian Population.

BACKGROUND

Postoperative atrial fibrillation (AF) is associated with increased morbidity, mortality, and resource utilization. Current prediction models for postoperative AF are based primarily on Western populations. In this study, we sought to develop a clinical prediction rule for postcardiac surgery AF for a multiethnic Asian population.

METHODS

Two thousand one hundred sixty-eight patients undergoing coronary artery bypass graft or valve surgery with cardiopulmonary bypass were prospectively enrolled in this observational study between August 2008 and July 2012 at Singapore's 2 national heart centers. Postoperative AF was defined as an irregularly irregular electrocardiogram rhythm without identifiable P wave after surgery and before hospital discharge that lasted more than an hour, or affected hemodynamics (ie, systolic blood pressure <90 mm Hg or mean arterial blood pressure <60 mm Hg), or required medical treatment. Patients had continuous telemetry monitoring for at least 72 hours while in the intensive care or high-dependency units postoperatively. Subsequently, patients had a 12-lead electrocardiogram daily and when symptomatic. Multivariable logistic regression was used to determine significant predictors of postcardiac surgery AF, and a scoring system was developed. The model was internally validated in an additional 500 patients.

RESULTS

Postoperative AF occurred in 17.3% of patients, with a peak occurrence in the first 72 hours after surgery. Multivariate logistic regression analysis identified age ≥65 years (odds ratio [OR], 1.44; 95% confidence interval [CI], 1.11-1.85, P = 0.005), history of AF (OR, 3.65; 95% CI, 2.52-5.30, P < 0.001), inotrope use (OR, 1.74; 95% CI, 1.31-2.32, P < 0.001), cardiopulmonary bypass duration >120 minutes (OR, 1.92; 95% CI, 1.47-2.52, P < 0.001), and Chinese ethnicity (Chinese versus Indian OR, 2.09; 95% CI, 1.28-3.41, P = 0.003) or Malay (Malay versus Indian OR, 2.43; 95% CI, 1.36-4.05, P = 0.002) to be independently associated with postoperative AF. The area under the receiver-operator characteristic curve of the model was 0.704 (95% CI, 0.674-0.734). Internal validation produced an area under the receiver-operator characteristic curve of 0.756 (95% CI, 0.690-0.821).

CONCLUSIONS

Clinical risk factors for AF after cardiac surgery in an Asian population are similar to that reported from primarily Western populations, but specific ethnicity influences susceptibility.