Prediction of new onset postoperative atrial fibrillation using a simple Nomogram

Abstract

Background: New onset postoperative atrial fibrillation (POAF) is the most common complication of cardiac surgery, with an incidence ranging from 15 to 50%. This study aimed to develop a new nomogram to predict POAF using preoperative and intraoperative risk factors.

Methods: We retrospectively analyzed the data of 2108 consecutive adult patients (> 18 years old) who underwent cardiac surgery at our medical institution. The types of surgery included isolated coronary artery bypass grafting, valve surgery, combined valve and coronary artery bypass grafting (CABG), or aortic surgery. Logistic regression or machine learning methods were applied to predict POAF incidence from a subset of 123 parameters. We also developed a simple nomogram based on the strength of the results and compared its predictive ability with that of the CHA2DS2-VASc and POAF scores currently used in clinical practice.

Results: POAF was observed in 414 hospitalized patients. Logistic regression provided the highest area under the receiver operating characteristic curve (ROC) in the validation cohort. A simple bedside tool comprising three variables (age, left atrial diameter, and surgery type) was established, which had a discriminative ability with a ROC of 0.726 (95% CI 0.693-0.759) and 0.727 (95% CI 0.676-0.778) in derivation and validation subsets respectively. The calibration curve of the new model was relatively well-fit (p = 0.502).

Conclusions: Logistic regression performed better than machine learning in predicting POAF. We developed a nomogram that may assist clinicians in identifying individuals who are prone to POAF.

Keywords: Atrial fibrillation; Cardiac surgery; Risk stratification; Surgical complications.

Fig. 1

The flow chart displays the inclusion and exclusion of patients

Fig. 2

Area under the ROC curve showing the performance of different models in predicting POAF in derivation (A) and validation (B) cohorts

Fig. 3

A constructed nomogram for predicting POAF. For surgical classification variables, their distributions are reflected by the box size (boxes 1 to 4 represent valve surgery, CABG, concomitant valve and CABG surgery, and aorta surgery, respectively). LAd left atrial diameter, Pr probability

Fig. 4

Area under the ROC curve depicts the performance of the nomogram, POAF score, and CHA2DS2-VASc score. CI confidence interval

Fig. 5

Calibration curve of the model in the derivation (A) and validation (B) cohort. The Y-axis represents the actual POAF incidence rate, and the x-axis represents the predicted rate. The diagonal line represents a perfect prediction by the ideal model. The red line represents the performance of the nomogram, of which a closer fit to the diagonal line represents a better prediction