A Signal Processing Framework for the Detection of Abnormal Cardiac Episodes

Abstract

Motivation: Cardiologists rely on the long duration Holter electrocardiogram (ECG) recordings in general for assessment of abnormal episodes and such process found to be tedious and time consuming. An automatic abnormal cardiac episode detection algorithm is the need of the hour that needs to be optimized to reduce the manual burden.

Objective: The current study presents a signal processing framework with a cross-database to detect abnormal episodes in long-term ECG signals.

Methodology: The data was pre-processed to remove power line interference and baseline drift using basis pursuit sparsely decomposed tunable-Q wavelet transform (BPSD-TQWT). A total of 44 features of time domain, frequency domain, and time-frequency domain characteristics were extracted from the ECG signal. This proposed work tested classification performance with support vector machine (SVM), K-nearest neighbour (KNN), decision tree, naïve Bayes, the nearest mean classifier, and the nearest root mean square classifiers. The trained models with open-source data were used to predict the abnormal episodes from the proprietary database and vice versa. Finally, the performance was analysed via recall rate, specificity, precision, F1-score, and accuracy.

Results: Among six classification models, SVM performed best. With an open-source database, the SVM model achieved 95.01% accuracy, and detected the abnormal episodes from proprietary database with an accuracy of 99.31%. In addition, with the proprietary database SVM model classified the normal-abnormal cardiac episodes with an accuracy of 99.89% and detected the abnormal episodes from proprietary database with an accuracy of 92.51%.

Conclusion: When the performance results were compared with the literature, it was observed that the proposed framework performed well. As a result, the proposed framework could be used in an autonomous diagnosis system.

Keywords: Abnormal cardiac episodes; Cross-database; Electrocardiogram; Nearest RMS classifier; Nearest mean classifier; Support vector machine.