title: Detection of inter-patient left and right bundle branch block heartbeats in ECG using ensemble classifiers.
abstract: BACKGROUND
  Left bundle branch block (LBBB) and right bundle branch block (RBBB) not only mask electrocardiogram (ECG) changes that reflect diseases but also indicate important underlying pathology. The timely detection of LBBB and RBBB is critical in the treatment of cardiac diseases. Inter-patient heartbeat classification is based on independent training and testing sets to construct and evaluate a heartbeat classification system. Therefore, a heartbeat classification system with a high performance evaluation possesses a strong predictive capability for unknown data. The aim of this study was to propose a method for inter-patient classification of heartbeats to accurately detect LBBB and RBBB from the normal beat (NORM).
  
  
  METHODS
  This study proposed a heartbeat classification method through a combination of three different types of classifiers: a minimum distance classifier constructed between NORM and LBBB; a weighted linear discriminant classifier between NORM and RBBB based on Bayesian decision making using posterior probabilities; and a linear support vector machine (SVM) between LBBB and RBBB. Each classifier was used with matching features to obtain better classification performance. The final types of the test heartbeats were determined using a majority voting strategy through the combination of class labels from the three classifiers. The optimal parameters for the classifiers were selected using cross-validation on the training set. The effects of different lead configurations on the classification results were assessed, and the performance of these three classifiers was compared for the detection of each pair of heartbeat types.
  
  
  RESULTS
  The study results showed that a two-lead configuration exhibited better classification results compared with a single-lead configuration. The construction of a classifier with good performance between each pair of heartbeat types significantly improved the heartbeat classification performance. The results showed a sensitivity of 91.4% and a positive predictive value of 37.3% for LBBB and a sensitivity of 92.8% and a positive predictive value of 88.8% for RBBB.
  
  
  CONCLUSIONS
  A multi-classifier ensemble method was proposed based on inter-patient data and demonstrated a satisfactory classification performance. This approach has the potential for application in clinical practice to distinguish LBBB and RBBB from NORM of unknown patients.
authors.affiliation: Department of Biomedical Engineering, School of Computer and Information Technology, Beijing Jiaotong University, 3 Shang Yuan Cun, Hai Dian District, Beijing, China. hfhuang@bjtu.edu.cn.
authors.forename: Huifang
authors.initials: H
authors.lastname: Huang
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhu
authors.forename: Ruiping
authors.initials: R
authors.lastname: Wang
authors.forename: Guangshu
authors.initials: G
authors.lastname: Hu
mesh_terms: D001499:Bayes Theorem; D002037:Bundle-Branch Block / Q000503:physiopathology*; D016002:Discriminant Analysis; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D012815:Signal Processing, Computer-Assisted; D013223:Statistics as Topic / Q000379:methods*; D060388:Support Vector Machine