Browser-Based Vectorcardiography Arrives as a Practical CRT Research Tool
VectBox Sync is a browser-based application built to extract vectorcardiographic measures of ventricular synchrony from standard 12-lead electrocardiograms. The preprint places the tool squarely in the long-standing gap between routine ECG interpretation and the more three-dimensional reality of ventricular activation. In cardiac resynchronization therapy research, that gap matters because QRS width and morphology remain the dominant electrical selection criteria, yet they do not fully capture how activation propagates through the ventricles in space and time.
A single QRS interval can look reassuring on paper while still masking substantial activation delay across different ventricular regions. VectBox Sync tries to make that hidden geometry visible.
The application implements a published vectorcardiographic dyssynchrony index and frames it as an exploratory assessment tool rather than a replacement for standard selection metrics. Its purpose is not to override guideline-based practice, but to add quantitative context when electrical timing is being interrogated in a more granular way. In a field where nonresponse to CRT remains common despite careful selection, a software platform that can turn routine ECG data into three-dimensional descriptors has obvious research appeal.
Native ECG Inputs, Optional Conversion, and a Structured Workflow
VectBox Sync accepts native digital ECG recordings and can also work with common clinical and research waveform formats. When only archived or paper-like sources are available, optional manufacturer-PDF import and externally digitized numerical files extend access. That matters in real-world electrophysiology work, where historical ECG repositories are often fragmented across systems and formats.
The workflow is intentionally straightforward. After optional preprocessing, the user selects a QRS interval, and the application calculates the dyssynchrony index relative to a calibrated control cutoff. Companion outputs include voltage and speed integrals, loop angles, and planarity, along with vectorcardiographic trajectories and synchrony-field maps. The package also generates a multilingual PDF report, which lowers the friction for teaching sessions, retrospective analysis, and cross-site comparison.
Quantitative descriptors with bedside logic
These outputs are not ornamental. Voltage and speed integrals summarize how electrical activity moves through the heart, while loop angles and planarity describe the shape and orientation of ventricular depolarization in vector space. In practical terms, a distorted or less planar loop can reflect disordered conduction and delayed propagation, the same physiology that can blunt the benefit of pacing if the chosen lead position fails to recruit the right substrate.
The application also allows labeled conditions from the same session to be overlaid for comparison, including successive pacing settings. That feature is particularly relevant for CRT optimization work, where a change in pacing configuration can alter activation patterns more meaningfully than a change in surface QRS duration alone.
Why Surface ECG Criteria Leave Clinical Blind Spots
Conventional CRT selection depends heavily on QRS duration and morphology because they are simple, reproducible, and available everywhere. Yet electrical synchrony is not a one-dimensional event. Ventricular activation unfolds across a three-dimensional myocardial architecture, and the surface ECG compresses that process into a limited projection. Two patients with similar QRS durations can therefore have very different intraventricular activation patterns and very different chances of response to pacing.
VectBox Sync is built around that biological problem. By translating a 12-lead ECG into vectorcardiographic form, the software attempts to recover spatial information that a conventional trace can obscure. The dyssynchrony index then gives users a numerical way to compare the observed activation pattern with a control cutoff derived from calibration. For researchers, that creates a bridge between routine ECG acquisition and a more mechanistic analysis of electrical delay.
The tool is available through a web interface at vectbox.com/sync for research and educational use. Its browser-based design lowers the barrier to entry for groups that do not have specialized standalone software installed on every workstation.
A Tool for Research, Education, and Pacing Comparisons
The strongest use case here is exploratory work. VectBox Sync can support studies of CRT candidacy, comparisons between pacing states, and educational demonstrations of how ventricular activation geometry shifts when conduction changes. Because it works with common waveform formats and can incorporate digitized numerical files, it may be especially useful when older ECGs need to be reanalyzed under a modern framework.
The multilingual PDF output is a pragmatic addition. In electrophysiology, communication often spans clinicians, engineers, and trainees, and a report that packages the derived metrics, trajectories, and maps into a single document can streamline review. That kind of output is more than cosmetic; it is how a complex signal-processing result becomes discussable at the bedside or in a conference room.
The preprint status still leaves important limits
This remains a preprint and has not been certified by peer review. No diagnostic accuracy metrics, outcome validation data, or patient-level performance estimates are provided in the abstract, so the clinical value of the dyssynchrony index still depends on external validation. The article also frames the platform as exploratory and educational rather than as a tool ready to direct treatment decisions.
Even so, the concept is concrete: use the ECG people already obtain, reconstruct the vectorcardiographic signal, and ask whether the three-dimensional activation pattern is more informative than QRS width alone. For CRT, where response remains imperfect and patient selection remains imperfect, that kind of software could help clarify why two apparently similar ECGs do not behave the same way once pacing enters the equation. The next test will be whether the index and its companion descriptors track with clinically meaningful response, not just with elegant signal display.