Commentary questions MEA method in canine ECG study

A methodological dispute has surfaced in canine cardiology research. In a July 29, 2026 commentary in Frontiers in Veterinary Science, Dragutin Novosel and colleagues argue that a 2025 paper on 12-lead ECG patterns in dogs with monomorphic ventricular tachycardia or complete bundle branch block used an unclear formula for calculating mean electrical axis in the frontal plane, and that the published values appear numerically consistent with an uncorrected calculation rather than the corrected one the paper cited. (frontiersin.org)

The original 2025 study by Perego, Maffei, Cavallini, and Santilli examined QRS complex configurations in dogs across four groups: sinus rhythm with right bundle branch block, sinus rhythm with left bundle branch block, monomorphic ventricular tachycardia with right bundle branch block morphology, and monomorphic ventricular tachycardia with left bundle branch block morphology. It described the work as the first canine electrocardiography study to evaluate 12-lead QRS configurations for monomorphic ventricular tachycardia and sinus rhythm with bundle branch block, aiming to sharpen ECG-based differentiation of wide-complex rhythms in dogs. (frontiersin.org)

Novosel’s commentary focuses narrowly on the MEA calculation, not the broader clinical interpretation. The authors say the formula described in the 2025 paper did not match the corrected equation Novosel originally published in 1999 for combining limb leads with augmented leads. That correction factor, 2/√3, has also been explained in later educational pieces by Novosel and others, which show that graphical or numerical axis estimates using lead I and aVF are only equivalent to standard methods if that correction is applied. (frontiersin.org)

To test the issue, the commentary authors say they obtained the raw data referenced in the original paper’s data availability statement and recalculated MEA values from the first heartbeat of all 103 included dogs. Their analysis found the reported MEA values were statistically indistinguishable from results generated without the correction factor and differed from values generated with the corrected equation. They also noted that a recently published paper from the same research group did account for the difference that arises when MEA is calculated from a combination of limb and augmented leads, suggesting the issue may be specific to the 2025 QRS-configuration study rather than a blanket methodological position. (frontiersin.org)

There doesn’t appear to be a public reply yet from the original study authors. Still, the commentary is measured in tone. Novosel and colleagues explicitly state that their critique does not necessarily undermine the original article’s conclusions, and they describe the methods of data acquisition and the broader ECG analysis in the 2025 study as well described. That framing matters, because the discussion is less about overturning a clinical message than about making sure future cardiology research uses the same mathematical language. (frontiersin.org)

Why it matters: For veterinary professionals, especially cardiologists, residents, and ECG-heavy referral practices, this is a useful example of how methodological precision affects downstream interpretation. MEA is a routine part of ECG assessment, and related canine work from Perego and colleagues has already contributed practical parameters for bundle branch block evaluation, including R-peak time thresholds with high reported sensitivity and specificity. If one paper uses an uncorrected axis calculation and another uses a corrected one, clinicians comparing studies, teaching trainees, or building internal reference frameworks may be comparing values that aren’t fully aligned. (cris.unibo.it)

The issue also lands at a time when veterinary ECG interpretation is becoming more data-driven, with growing interest in computer-assisted analysis and standardized diagnostic criteria. Prior research has shown that even different digital electrocardiographs and analysis programs can produce clinically significant differences in canine ECG values and reference intervals. Against that backdrop, a debate over one correction factor may sound small, but it fits a bigger industry push toward reproducibility, harmonized methods, and cleaner translation from published research into practice. (pmc.ncbi.nlm.nih.gov)

What to watch: The next signal will be whether Frontiers publishes a response, corrigendum, or methodological clarification tied to the 2025 article, and whether future canine ECG studies begin stating their MEA formulas more explicitly, including when leads I and aVF are used together. (frontiersin.org)