This study aimed to investigate new-onset heart blocks after noncardiac surgery, identify risk factors, and develop a prediction model.

Objective: This study aimed to investigate new-onset heart blocks after noncardiac surgery, identify risk factors, and develop a prediction model.

Methods: A retrospective cohort study included 281,497 patients aged 18 or older who underwent noncardiac surgery at a single center between Jan 2008 and Aug 2019. The main outcome was postoperative new-onset heart blocks within one year, including atrioventricular and bundle blocks. Prognostic impact was assessed using Kaplan-Meier survival curves and time-dependent Cox regression analysis. Perioperative data was used for machine learning models (logistic regression, support vector machine, random forest, decision tree). Model performance was measured using the area under the receiver operating characteristic curve (AUC).

Inclusion Criteria:

• patients above 18 yrs undergoing noncardiac surgery at the First Medical Center of the Chinese People's Liberation Army General Hospital (PLAGH) from January 1, 2008 to August 1, 2019.

Exclusion Criteria:

• surgical duration of less than 30 minutes
• incomplete data

Data were gathered from electronic medical records (EMRs) for all patients undergoing noncardiac surgery at the First Medical Center of the Chinese People's Liberation Army General Hospital (PLAGH) from January 1, 2008 to August 1, 2019. Patients with a surgical duration of less than 30 minutes or age <18 years were excluded. Input data elements were extracted from the patient anesthesia and medical records. The survival data one year after surgery were obtained from medical records and telephone follow-up records confirmed by the Chinese Center for Disease Control and Prevention (CCDC)