Automatic classification of long-term ambulatory ECG records according to type of ischemic heart disease
1University of Ljubljana, Faculty of Computer and Information Science, Tržaška 25, 1000 Ljubljana, Slovenia. ales.smrdel@fri.uni-lj.si
Insights
An automated algorithm accurately analyzes ambulatory electrocardiographic (AECG) data to distinguish between elevated and depressed ST segment episodes, aiding in the classification of ischemic heart disease types.
Area of Science:
- Cardiology
- Biomedical Engineering
- Medical Informatics
Background:
- Ambulatory electrocardiographic (AECG) records show distinct ST segment patterns in different types of myocardial ischemia.
- Elevated ST segments typically indicate transmural ischemia (e.g., Prinzmetal's angina), while depressed segments suggest subendocardial ischemia (e.g., unstable or stable angina).
- The large volume of AECG data necessitates automated analysis methods for accurate interpretation.
Purpose of the Study:
- To develop and evaluate an algorithm for automatically determining the type of transient ischemic episodes (ST segment elevations or depressions) in AECG records.
- To classify AECG records based on the type of ischemic heart disease present, including Prinzmetal's angina, other coronary artery diseases, and other heart diseases.
Main Methods:
- The algorithm was developed and tested using 24-hour AECG records from the Long Term ST Database (LTST DB).
- It generates ST segment level and reference functions to derive ST segment deviation functions, accounting for non-ischemic changes.
- The algorithm uses the third statistical moment of the ST segment deviation function's histogram to identify ST segment deflections and classify ischemic events.
Main Results:
- The algorithm correctly identified the type of ST segment deflections in the majority of leads across 74 LTST DB records.
- It accurately classified most Prinzmetal's angina records (7/8) and other coronary artery disease records (47/55).
- Classification accuracy for other heart diseases was 1 out of 11 records.
Conclusions:
- The developed algorithm is efficient and suitable for processing extensive AECG data.
- It demonstrates effectiveness in classifying the majority of records based on transient ischemic heart disease type.
- This automated approach aids in the analysis of complex AECG data for improved diagnostic capabilities.
Background:
Elevated transient ischemic ST segment episodes in the ambulatory electrocardiographic (AECG) records appear generally in patients with transmural ischemia (e. g. Prinzmetal's angina) while depressed ischemic episodes appear in patients with subendocardial ischemia (e. g. unstable or stable angina). Huge amount of AECG data necessitates automatic methods for analysis. We present an algorithm which determines type of transient ischemic episodes in the leads of records (elevations/depressions) and classifies AECG records according to type of ischemic heart disease (Prinzmetal's angina; coronary artery diseases excluding patients with Prinzmetal's angina; other heart diseases).
Methods:
The algorithm was developed using 24-hour AECG records of the Long Term ST Database (LTST DB). The algorithm robustly generates ST segment level function in each AECG lead of the records, and tracks time varying non-ischemic ST segment changes such as slow drifts and axis shifts to construct the ST segment reference function. The ST segment reference function is then subtracted from the ST segment level function to obtain the ST segment deviation function. Using the third statistical moment of the histogram of the ST segment deviation function, the algorithm determines deflections of leads according to type of ischemic episodes present (elevations, depressions), and then classifies records according to type of ischemic heart disease.
Results:
Using 74 records of the LTST DB (containing elevated or depressed ischemic episodes, mixed ischemic episodes, or no episodes), the algorithm correctly determined deflections of the majority of the leads of the records and correctly classified majority of the records with Prinzmetal's angina into the Prinzmetal's angina category (7 out of 8); majority of the records with other coronary artery diseases into the coronary artery diseases excluding patients with Prinzmetal's angina category (47 out of 55); and correctly classified one out of 11 records with other heart diseases into the other heart diseases category.
Conclusions:
The developed algorithm is suitable for processing long AECG data, efficient, and correctly classified the majority of records of the LTST DB according to type of transient ischemic heart disease.
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