Abstract 17749: Regionalization of Non-Pulmonary Vein Triggers for Atrial Fibrillation When the P Wave is Obscured Using Non-Invasive Electrocardiographic Imaging QRS-T Subtraction Algorithm
Bibliographic record
Abstract
Introduction: Ablation of non-pulmonary vein triggers (NPVTs) after pulmonary vein isolation (PVI) may reduce atrial fibrillation (AF) recurrence. Localizing a trigger which initiates AF after a single atrial ectopic beat is challenging, especially in the scenario when the trigger P wave is obscured by preceding QRS-T complex. Aim: To evaluate the potential for noninvasive electrocardiographic imaging (ECGi) to localize NPVTs when the P wave morphology is superimposed on the T wave of the previous beat. Methods: We developed an algorithm which overlays and subtracts the preceding QRS-T wave complex from the QRS-T wave complex which is obscuring the P wave of interest, thus revealing the P wave morphology (Figure 1A). Resultant unobscured P waves (from multiple body surface electrodes) are then used for ECGi computation. In five patients undergoing AF ablation, after PVI, we paced from 15 atrial sites where NPVTs commonly arise, and evaluated the epicardial activation maps generated by ECGi both when pacing was timed to ensure an unobscured P wave and when timed to coincide with preceding QRS-T complex. Co-registration of CT-based ECGi activation maps with invasive electroanatomic map (EAM) allowed comparison of the earliest activation site on ECGi map from both the obscured P waves after QRS-T subtraction and unobscured P waves with true pacing locations on EAM (Figure 1B). Results: From 146 pacing sites in our patient cohort, for the unobscured P waves, median distance between earliest site on ECGi map and EAM pacing location was 16 mm (10-21 mm), and for obscured P waves after QRS-T subtraction, median distance was also 16 mm (12-23 mm) (Figure 1C). Conclusion: Using a QRS-T subtraction algorithm, ECGi can approximate origin of paced P waves whether P wave is unobscured or obscured by the preceding QRS-T complex. Spontaneous NPVT P waves are commonly obscured by the QRS-T wave and the ability to rapidly localize an early coupled P wave may facilitate NPVT mapping and ablation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".