Table 1.
Table of abbreviations.
Fig 1.
The motivation box illustrates the prediction of “FS presence” (shaded in blue), “FS location” (shaded in green), and “AF sustainability” (shaded in red) in selecting the ablation targets for AF, where shaded rectangles indicate the composition of the positive class for each classifier. Note that the initiator-type FS is in both classes of “FS presence” and “AF sustainability”. The bold italic fonts mark the four simulation categories in our synthetic dataset. Steps 1 to 3 describe the training process of our classifiers on synthetic data, and Step 4 illustrates the application of the trained classifiers on patient signals to non-invasively detect their AF mechanisms. In Step 1, white spheres show phase singularity (PS) points, the red arrows show the wavefront movement of rotors, and the red stars mark the focal sites.
Fig 2.
Rotor duration (“Rotor dur.” given by the bars) and AF inducibility (“AF ind.”, given by the line plot) as functions of CL of FS on LA, RA and PVs, with (“+”) or without (“−”) ACh.
Vertical bars of the line plot show the 95% confidence interval of the mean of all patient meshes. CL groups accounting for less than 5% of FS in each panel were excluded from analysis and the bar charts. n.u.: normalized unit.
Fig 3.
Simulations on the atrial mesh of Patient 2 of (a) an initiator-type FS with a CL of 180 ms at an LA focal site (αLA = 0.2, βLA = 0.2, red star), and (b) a driver-type FS with a CL of 210 ms at the same site (red star), with full videos (S1 and S2 Videos).
The white spheres in (a) show phase singularity points, and the red arrows show the wavefront movement of rotors. The time since the first firing of the FS was indicated above each frame. A sustained rotor of total duration 547 ms was presented in (a), but no rotor was detected in (b).
Fig 4.
Local activation time maps (a–c) and action potential duration maps (d–f) following a discharge of an FS (red stars) from the same site on the LA posterior wall (αLA = 0.4, βLA = 0.2), on the atrial mesh of Patient 1, under focal cycle lengths of 150 ms and 180 ms, with (“+”) and without (“−”) ACh.
The directions of wavefront propagation from the FS were shown by the black arrows. A gray color indicates tissue that was not excitable. Isochrone lines are drawn at an interval of 10ms. The focal activation was propagated at (a) and (c) but was blocked at (b). (f) shows the highest spatial heterogeneity in the action potential duration.
Table 2.
Testing scores using nested leave-one-patient-out cross validation on all classification tasks over five patients, using features of SO-BSS, AFFTr2DF and NDI.
Bold fonts mark the highest scores and the corresponding features.
Fig 5.
Means (points) and standard deviations (shaded areas) of the test accuracy scores using leave-one-patient-out cross validation, for changing K and lead systems (ECGs or BSPMs), on the classification tasks, with the best K for the highest accuracy (ECGBest or BSPMBest) in each setting shown by vertical bars.
Fig 6.
Meshes of five patient atria, and locations of 252 vest leads to compute BSPMs.
Each column shows the data for one patient. The top row shows the front view and the bottom row shows the top view. Inter-patient variations of atrial shapes and positions are visible.
Fig 7.
Two-dimensional PCA representation of MaxAC values obtained from SO-BSS with K = 10 over simulated BSPMs), on each patient and all pooled, for different colour-coded groupings: (a) all categories over all episodes, and (b) focal CLs over all FS episodes.
Clustering based on categories and focal CLs can be seen for each patient. a.u.: arbitrary unit.
Table 3.
Groupings and counts of patient-level mechanisms (by row), as well as the assignment of the patient group for survival analysis in Fig 8, based on whether a patient contains initiator-type FS coming from a single atrium.
This table omits the results of patients with driver-type FS for clarity.
Fig 8.
Kaplan–Meier curves of two paroxysmal AF patient groups, showing the post-ablation AF-free likelihoods up to three years.
The grouping was according to whether the AF episodes in the patient were predicted as driven by initiator-type FS originating from a single atrium. The shading shows the 95% confidence interval of the Kaplan–Meier curves. The first group had better two-year and three-year AF-free outcomes than the other group, with p-values of logrank tests both < 0.01. n.u.: normalized unit.
Table 4.
Computation of signal-level mechanisms from the positive (“+”) or negative (“−”) prediction outputs of our classifiers.
Note that FS location classifier outputs whether the FS is on RA.