Heart rate variability parameters in horses distinguish atrial fibrillation from sinus rhythm before and after successful electrical cardioversion.

This study aims to determine whether heart rate variability (HRV) parameters can differentiate between atrial fibrillation (AF) and sinus rhythm (SR) in horses, which could provide a diagnostic tool for horses at risk of AF reoccurrence.

Objective of the Study

The research sets out to explore if atrial fibrillation (AF), a common pathological arrhythmia in horses, can be differentiated from the normal sinus rhythm (SR) using heart rate variability parameters. This work arises from the need to have an effective tool to monitor horses susceptible to AF’s reoccurrence, especially since these animals often experience the condition again after successful treatment.

Methodology

• The methodology involves a cohort study composed of 20 horses, where each horse served as its own control.
• For both AF and SR status in horses, six heart rate variability parameters were determined at rest and during various physical activities such as walking and trotting.
• The researchers utilized time-domain parameters (like standard deviation of the NN intervals and root mean squared successive differences in NN intervals), frequency-domain parameters (such as low/high-frequency ratio), and nonlinear parameters (including standard deviation of the Poincaré plot).
• The statistical analysis involved paired Wilcoxon signed rank tests and receiver operating characteristic curves.

Results

• The findings showed that horses’ heart rate variability was higher during atrial fibrillation compared to the normal sinus rhythm.
• The detection of atrial fibrillation with most HRV parameters was good, with some like the root mean squared successive differences in NN intervals, providing excellent results.
• The sensitivity and specificity of all parameters were high, recording the highest during exercise.
• Even though the area under the curve (AUC) improved with longer recordings, short recordings still performed well in detecting atrial fibrillation.

Conclusions

In conclusion, the evidence suggests that it’s indeed possible to distinguish between atrial fibrillation and sinus rhythm in horses using HRV parameters. This discovery offers potential for developing a practical monitoring tool for equines at risk of atrial fibrillation, providing an easier, non-invasive way to monitor and prevent the reoccurrence of the condition. However, because the study made use of the subjects as their own control and didn’t incorporate long-term follow-up data, more research is needed to solidify these findings and develop the monitoring tool.