Key result
A cutoff of 6% maximum R-R shortening during the recovery phase predicted the presence of arrhythmia with 88% sensitivity, 97% specificity, and a likelihood ratio of 26.
Why the study?
Little is known about normal heart rate variability in horses during exercise, making it difficult to separate premature beats from normal beat-to-beat variation at higher heart rates.
Does heart rate variability analysis accurately detect arrhythmias in horses undergoing a standard treadmill exercise test?
Observational (n=54)
Does heart rate variability analysis accurately detect arrhythmias in horses undergoing a standard treadmill exercise test?
In horses undergoing treadmill exercise, an instantaneous R-R interval shortening of more than 6% during the recovery phase is highly predictive of an arrhythmic event.
May support arrhythmia screening via recovery-phase analysis in veterinary patients; hypothesis-generating and requires prospective validation before clinical adoption.
BACKGROUND: Little is known about normal heart rate variability (HRV) in horses during exercise. It can be difficult to separate premature beats from normal beat-to-beat variation at higher heart rates. OBJECTIVES: The aim was to quantify HRV in healthy horses during a high-speed treadmill-standardized exercise test (HSET) and to compare with the HRV in horses observed to have arrhythmias during exercise. ANIMALS: Thirteen healthy horses (Group H), 30 horses with arrhythmias (Group A), and 11 horses with poor performance but no observed arrhythmias (Group O). METHODS: Prospective, observational study. All horses performed a HSET with simultaneous electrocardiograph (ECG) recorded. The ECGs were corrected for artifacts, and arrhythmias noted. Percent instantaneous beat-to-beat cycle length variation (% R-R variation) was calculated, and HRV analyses were performed on trot, canter, and recovery segments. RESULTS: Group H showed between -4.4 and +3.8% R-R variation during trot and between -6.1 and +5.4% R-R variation during the canter phase of the HSET. Group A had significantly larger maximum and 1st percentile R-R shortening and lengthening compared with Group H and Group O during the recovery phase where most arrhythmias were observed. During recovery, a cutoff of 6% maximum % R-R shortening predicted the presence of arrhythmia with 88% sensitivity and 97% specificity and likelihood ratio of 26. CONCLUSIONS AND CLINICAL IMPORTANCE: Healthy horses have little instantaneous R-R variation during exercise. If a cardiac cycle shortens more than 6% from the previous cycle during the recovery phase, this R-R interval is likely to represent an arrhythmic event.
No takes yet. Share an insight, caveat, or question.
Frick et al. (2018) conducted an observational in Arrhythmias (n=54). Maximum % R-R shortening > 6% vs. Maximum % R-R shortening ≤ 6% was evaluated on Presence of arrhythmia during recovery phase (Likelihood ratio 26). A cutoff of 6% maximum R-R shortening during the recovery phase predicted the presence of arrhythmia with 88% sensitivity, 97% specificity, and a likelihood ratio of 26.
Synapse has enriched 5 related papers. Consider them for comparative context: