Magnetocardiography-Based Ischemic Heart Disease Detection and Localization Using Machine Learning Methods.

OBJECTIVE: This study focused on developing a fast and accurate automatic ischemic heart disease detection/localization methodology. METHODS: T wave was segmented from averaged Magnetocardiography (MCG) recordings and 164 features were subsequently extracted. These features were categorized into three groups: time domain features, frequency domain features, and information theory features. Next, we compared different machine learning classifiers including: k-nearest neighbor, decision tree, support vector machine (SVM), and XGBoost. To identify ischemia heart disease (IHD) case, we selected three classifiers with best performance and applied model ensemble to average results. All 164 features were used in this stage. To localize ischemia, we classified IHD group according to stenosis locations, including left anterior descending (LAD), left circumflex artery (LCX), and right coronary artery (RCA). For this task, we used XGBoost classifier and 18 time domain features. RESULTS: For IHD detection, the SVM-XGBoost model achieved best results with accuracy = 94.03%, precision = 86.56%, recall = 97.78%, F-score = 92.79%, AUC = 0.98, and average precision = 0.98. For ischemia localization, XGBoost model achieved accuracy = 0.74, 0.68, and 0.65, for LAD, LCX, and RCA, respectively. CONCLUSION: we have developed an automatic IHD detection and localization system. We find that 1. T wave repolarization synchronicity is an important factor to distinguish IHD from normal subjects 2. Magnetic field pattern is associated with stenosis location. SIGNIFICANCE: The proposed machine learning method provides the clinicians a fast and accurate diagnosis tool to interpret MCG data, boosting its acceptance into clinics. Furthermore, the magnetic pole characteristics revealed by the method shows to be related to ischemia location, presenting the opportunity to noninvasively locate ischemia.

Relationship between augmentation index and severity of coronary artery disease / 中国实用内科杂志

Objective To explore whether augmentation index is an independent risk factor for coronary heart disease or not,and the relationship between augmentation index and coronary artery disease severity.Methods In the study,245 subjects who were hospitalized between Dec.2003 and Dec.2004,were classified into 4 groups and their clinical and biological characteristics and the summary of the scores in each of the eight segment and aortic pressure waveform in ascending aorta were recorded respectively.Results The larger the augmentation index was,the more the number of coronary stenosis vessels was.Linear regression analysis indicated that augmentation index was significantly correlated with grade of coronary stenosis.When augmentation index was more than 45%,the sensibility and specificity was 91.5%and 92.6%respectively.In the logistic regression model,augmentation index was the independent risk factor for coronary heart disease,and the odds ratio of coronary heart disease was 1.893.The 95%CI was 1.421~2.521.Conclusion Augmentation index is an independent risk factor for coronary heart disease and a predictor of angiographic coronary artery disease severity.