TDK conference 2024

The long-term use of an implantable cardiac monitor (loop recorder) in a horse has been reported previously, but its exact diagnostic role is still unclear. The aim of our study was to investigate the long-term applicability of the Reveal XT cardiac monitor for recording normal heart rhythm and some arrhythmias in adult horses. Twelve animals were implanted with the device in standing position under sedation and local anaesthesia. One horse in the population had a history of persistent atrial fibrillation. The other animals were healthy. The events recorded by the cardiac monitors using the built-in human algorithm were as follows: total number of episodes, ventricular tachyarrhythmia, fast ventricular tachyarrhythmia, asystole, bradycardia, atrial tachycardia, atrial fibrillation, and percentage of time spent in atrial tachycardia and atrial fibrillation. The median duration of data collection was 1169 days. The proper functioning of the cardiac monitors was verified with a Televet II electrocardiograph, which has been validated and used in equine cardiology. We observed an extremely high number of false positive detections for asystole and bradycardia. For atrial fibrillation, false positive detections occurred in five horses and false negative in one individual. The present study showed that long-term use of the Reveal XT cardiac monitor is feasible and well tolerated by the horses, and the devices performed reliably without complications. The human algorithm could not be used for automatic detection of arrhythmic episodes in the study population. The device was able to detect atrial fibrillation, but the recorded percentage of time spent in atrial fibrillation was inaccurate and stored ECGs had to be manually interpreted. Since the human analysis algorithm of the cardiac monitor could not identify bradyarrhythmias in horses based on our results, this device is not suitable for accurately determining the aetiology of episodic collapse in this species.