Relationship between atrial fibrillatory rate based on analysis of a modified base-apex surface electrocardiogram analysis and the results of transvenous electrical cardioversion in horses with spontaneous atrial fibrillation.

The research article delves into a comparative study of the atrial fibrillatory rate derived from a local right atrial intracardiac recording and a single-lead surface electrocardiogram during atrial fibrillation in horses. The purpose is to find any correlation with transvenous electrical cardioversion threshold, the number of shocks and the success rate of the cardioversion.

Methods

• The researchers examined ECGs and clinical records of horses suffering from atrial fibrillation (AF) that had been treated with transvenous electrical cardioversion (TVEC).
• The study only included those horses for which a simultaneous recording of the right atrial intracardiac electrogram and a modified base-apex ECG was accessible.
• The research team selected three-minute long episodes of simultaneous electrograms and surface ECG during AF for analysis. The comparison was carried out using Bland-Altman analysis.
• The mean RA-FR (fibrillatory rate from right atrial intracardiac recording) was calculated from the deflections on the intracardiac electrogram. Conversely, the AFR (atrial fibrillatory rate from a single-lead surface ECG) was extracted from the surface ECG using spatiotemporal QRS and T-wave cancellation.

Results

• A total of 73 horses fulfilled the criteria for inclusion in the study. The average difference between RA-FR and AFR was found to be -13 fibrillations per minute (fpm).
• The 95% limits of agreement were between -66 and 40 fpm. A moderate correlation (ρ = 0.65) was found between RA-FR and AFR (p < 0.001).
• The researchers observed that neither RA-FR nor AFR appeared to influence the TVEC cardioversion threshold or the number of TVEC shocks applied during treatments.

Conclusions

• The results suggest that AFR might facilitate non-invasive long-term monitoring of AF dynamics in horses.
• Furthermore, neither RA-FR nor AFR could be utilized as predictive measures for determining the minimal defibrillation threshold for TVEC, indicating a lack of their practical application in tailoring AF treatment strategies.