The purpose of this retrospective study is to evaluate the clinical performance of SMD-AFECG, an artificial intelligence-based medical device software that predicts the risk of atrial fibrillation occurring within 2 hours using single-lead electrocardiogram data. A total of 797 eligible electrocardiogram datasets collected through VitalDB at Seoul National University Hospital will be included. The performance of SMD-AFECG will be evaluated separately for new-onset atrial fibrillation in patients without a previous history of atrial fibrillation (NOAF) and atrial fibrillation episodes in patients with a previous history of atrial fibrillation (RAF). Two physicians blinded to the software results will review the electrocardiogram data and relevant medical records to establish the reference-standard classification. The blinded electrocardiogram datasets will then be analyzed using SMD-AFECG, and the software-generated predictions will be compared with the reference standard to evaluate the area under the receiver operating characteristic curve for NOAF and RAF.
This clinical study is designed as a retrospective, single-center, single-arm, superiority confirmatory clinical performance study. Pre-screening Electronic medical records and the VitalDB database at Seoul National University Hospital will be reviewed to identify potentially eligible data. The study will use continuous single-lead electrocardiogram data collected through VitalDB between September 1, 2022, and before September 30, 2025, from patients who were 19 years of age or older at the time of data collection. Screening and Data Collection A screening number will be assigned sequentially to each potentially eligible case. Eligibility will be determined by reviewing the predefined inclusion and exclusion criteria. For eligible cases, continuous single-lead electrocardiogram data, signal loss, heart rate, the occurrence and timing of atrial fibrillation episodes, the electrocardiogram collection period, demographic information, previous history of atrial fibrillation, and pregnancy status will be collected. Directly identifying personal information will not be collected. Test Dataset Creation Eligible data will be classified according to the presence or absence of a previous history of atrial fibrillation and the occurrence of an atrial fibrillation episode. The datasets will be categorized as new-onset atrial fibrillation positive or negative and repeated atrial fibrillation positive or negative. A subject number will then be assigned to each eligible dataset. The planned sample size is 797 cases, including 462 cases for the evaluation of new-onset atrial fibrillation and 335 cases for the evaluation of repeated atrial fibrillation. Reference Standard Establishment Two physicians with at least 5 years of relevant clinical experience will independently review the electrocardiogram data and relevant medical records. They will assess the suitability of the electrocardiogram data, confirm the presence or absence and timing of atrial fibrillation episodes, and verify the previous history of atrial fibrillation. Any disagreement between the physicians will be resolved according to the procedures specified in the study protocol. The final agreed classification will be used as the reference standard. Application of the Investigational Device The medical device operator will receive the test electrocardiogram datasets labeled only with screening numbers and will not be provided with the reference-standard results or positive or negative group classifications. The blinded datasets will be analyzed using SMD-AFECG to generate the predicted risk of atrial fibrillation occurring within 2 hours. The software-generated results will be recorded in the electronic data capture system. Statistical Analysis The software-generated predictions will be compared with the reference-standard classifications. The primary performance measures are the areas under the receiver operating characteristic curves for the prediction of new-onset atrial fibrillation and repeated atrial fibrillation. Two-sided 95% confidence intervals will be calculated using DeLong's method with a Wald-type confidence interval. The performance criterion for new-onset atrial fibrillation will be met if the lower bound of the 95% confidence interval for the area under the curve is greater than 0.7753. The performance criterion for repeated atrial fibrillation will be met if the corresponding lower bound is greater than 0.8299. The study will be considered successful only if both primary performance criteria are met. Secondary performance measures include the area under the precision-recall curve, precision, recall, F1 score, sensitivity, specificity, positive predictive value, negative predictive value, confusion-matrix results at different thresholds, and prediction time horizon. Because this is a retrospective study using previously collected data, there will be no direct participant contact, additional examination, treatment, or change in clinical care.
Study Type
OBSERVATIONAL
Enrollment
797
AUROC of SMD-AFECG for Predicting New-Onset Atrial Fibrillation Within 2 Hours
The area under the receiver operating characteristic curve (AUROC) will be calculated by comparing the maximum risk score generated by SMD-AFECG with the reference-standard classification of the NOAF-positive and NOAF-negative ECG datasets. A two-sided 95% confidence interval will be estimated using DeLong's method with a Wald-type confidence interval. The performance criterion will be met if the lower bound of the 95% confidence interval is greater than 0.7753.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases (up to 2 hours)
AUROC of SMD-AFECG for Predicting Repeated Atrial Fibrillation Within 2 Hours
The area under the receiver operating characteristic curve (AUROC) will be calculated by comparing the maximum risk score generated by SMD-AFECG with the reference-standard classification of the RAF-positive and RAF-negative ECG datasets. A two-sided 95% confidence interval will be estimated using DeLong's method with a Wald-type confidence interval. The performance criterion will be met if the lower bound of the 95% confidence interval is greater than 0.8299.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases (up to 2 hours)
AUPRC of SMD-AFECG for Predicting New-Onset Atrial Fibrillation Within 2 Hours
The area under the precision-recall curve (AUPRC) will be calculated from the relationship between precision and recall using the reference-standard NOAF-positive and NOAF-negative ECG datasets. AUPRC ranges from 0 to 1, with higher values indicating better identification of positive cases.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
AUPRC of SMD-AFECG for Predicting Repeated Atrial Fibrillation Within 2 Hours
The area under the precision-recall curve (AUPRC) will be calculated from the relationship between precision and recall using the reference-standard RAF-positive and RAF-negative ECG datasets. AUPRC ranges from 0 to 1, with higher values indicating better identification of positive cases.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Sensitivity of SMD-AFECG for Predicting New-Onset Atrial Fibrillation Within 2 Hours
At each evaluated threshold, sensitivity, also referred to as recall, will be calculated as the proportion of reference-standard NOAF-positive ECG datasets classified as positive by SMD-AFECG.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Sensitivity of SMD-AFECG for Predicting Repeated Atrial Fibrillation Within 2 Hours
At each evaluated threshold, sensitivity, also referred to as recall, will be calculated as the proportion of reference-standard RAF-positive ECG datasets classified as positive by SMD-AFECG.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Specificity of SMD-AFECG for Predicting New-Onset Atrial Fibrillation Within 2 Hours
At each evaluated threshold, specificity will be calculated as the proportion of reference-standard NOAF-negative ECG datasets classified as negative by SMD-AFECG.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Specificity of SMD-AFECG for Predicting Repeated Atrial Fibrillation Within 2 Hours
At each evaluated threshold, specificity will be calculated as the proportion of reference-standard RAF-negative ECG datasets classified as negative by SMD-AFECG.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Positive Predictive Value of SMD-AFECG for New-Onset Atrial Fibrillation
At each evaluated threshold, positive predictive value, also referred to as precision, will be calculated as the proportion of ECG datasets classified as positive by SMD-AFECG that are NOAF-positive according to the reference standard.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Positive Predictive Value of SMD-AFECG for Repeated Atrial Fibrillation
At each evaluated threshold, positive predictive value, also referred to as precision, will be calculated as the proportion of ECG datasets classified as positive by SMD-AFECG that are RAF-positive according to the reference standard.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Negative Predictive Value of SMD-AFECG for New-Onset Atrial Fibrillation
At each evaluated threshold, negative predictive value will be calculated as the proportion of ECG datasets classified as negative by SMD-AFECG that are NOAF-negative according to the reference standard.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific Negative Predictive Value of SMD-AFECG for Repeated Atrial Fibrillation
At each evaluated threshold, negative predictive value will be calculated as the proportion of ECG datasets classified as negative by SMD-AFECG that are RAF-negative according to the reference standard.
Time frame: At each evaluated threshold, negative predictive value will be calculated as the proportion of ECG datasets classified as negative by SMD-AFECG that are RAF-negative according to the reference standard.
Threshold-Specific F1 Score of SMD-AFECG for Predicting New-Onset Atrial Fibrillation
At each evaluated threshold, the F1 score will be calculated as the harmonic mean of precision and recall for the classification of NOAF-positive and NOAF-negative ECG datasets. Values range from 0 to 1, with higher values indicating better performance.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Threshold-Specific F1 Score of SMD-AFECG for Predicting Repeated Atrial Fibrillation
At each evaluated threshold, the F1 score will be calculated as the harmonic mean of precision and recall for the classification of RAF-positive and RAF-negative ECG datasets. Values range from 0 to 1, with higher values indicating better performance.
Time frame: During the AF-free ECG window immediately preceding AF onset for positive cases or the selected index time for negative cases, up to 2 hours
Prediction Time Horizon of SMD-AFECG for New-Onset Atrial Fibrillation
The prediction time horizon will be calculated as the time interval, in minutes, between the SMD-AFECG prediction or alarm and the onset of the reference-standard first atrial fibrillation episode among NOAF-positive ECG datasets.
Time frame: Within the 2-hour period before the onset of the first atrial fibrillation episode
Prediction Time Horizon of SMD-AFECG for Repeated Atrial Fibrillation
The prediction time horizon will be calculated as the time interval, in minutes, between the SMD-AFECG prediction or alarm and the onset of the reference-standard atrial fibrillation episode among RAF-positive ECG datasets.
Time frame: Within the 2-hour period before the onset of the atrial fibrillation episode
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