TY - JOUR

T1 - Electrocardiographic characteristics of trained and untrained standardbred racehorses

AU - Nissen, Sarah D.

AU - Weis, Rikke

AU - Krag-Andersen, Elisabeth K.

AU - Hesselkilde, Eva M.

AU - Isaksen, Jonas L.

AU - Carstensen, Helena

AU - Kanters, Jørgen K.

AU - Linz, Dominik

AU - Sanders, Prashanthan

AU - Hopster-Iversen, Charlotte

AU - Jespersen, Thomas

AU - Pehrson, Steen

AU - Buhl, Rikke

N1 - Publisher Copyright: © 2022 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.

PY - 2022

Y1 - 2022

N2 - Background: Long-term exercise induces cardiac remodeling that potentially influences the electrical properties of the heart. Hypothesis/objectives: We assessed whether training alters cardiac conduction in Standardbred racehorses. Animals: Two hundred one trained and 52 untrained Standardbred horses. Methods: Cross-sectional study. Resting ECG recordings were analyzed to assess heart rate (HR) along with standard ECG parameters and for identification of atrial and ventricular arrhythmias. An electrophysiological study was performed in 13 horses assessing the effect of training on sinoatrial (SA) and atrioventricular (AV) nodal function by sinus node recovery time (SNRT) and His signal recordings. Age and sex adjustments were implemented in multiple and logistic regression models for comparison. Results: Resting HR in beats per minute (bpm) was lower in trained vs untrained horses (mean, 30.8 ± 2.6 bpm vs 32.9 ± 4.2 bpm; P =.001). Trained horses more often displayed second-degree atrioventricular block (2AVB; odds ratio, 2.59; P =.04). No difference in SNRT was found between groups (n = 13). Mean P-A, A-H, and H-V intervals were 71 ± 20, 209 ± 41, and 134 ± 41 ms, respectively (n = 7). We did not detect a training effect on AV-nodal conduction intervals. His signals were present in 1 horse during 2AVB with varying H-V interval preceding a blocked beat. Conclusions and Clinical Importance: We identified decreased HR and increased frequency of 2AVB in trained horses. In 5 of 7 horses, His signal recordings had variable H-V intervals within each individual horse, providing novel insight into AV conduction in horses.

AB - Background: Long-term exercise induces cardiac remodeling that potentially influences the electrical properties of the heart. Hypothesis/objectives: We assessed whether training alters cardiac conduction in Standardbred racehorses. Animals: Two hundred one trained and 52 untrained Standardbred horses. Methods: Cross-sectional study. Resting ECG recordings were analyzed to assess heart rate (HR) along with standard ECG parameters and for identification of atrial and ventricular arrhythmias. An electrophysiological study was performed in 13 horses assessing the effect of training on sinoatrial (SA) and atrioventricular (AV) nodal function by sinus node recovery time (SNRT) and His signal recordings. Age and sex adjustments were implemented in multiple and logistic regression models for comparison. Results: Resting HR in beats per minute (bpm) was lower in trained vs untrained horses (mean, 30.8 ± 2.6 bpm vs 32.9 ± 4.2 bpm; P =.001). Trained horses more often displayed second-degree atrioventricular block (2AVB; odds ratio, 2.59; P =.04). No difference in SNRT was found between groups (n = 13). Mean P-A, A-H, and H-V intervals were 71 ± 20, 209 ± 41, and 134 ± 41 ms, respectively (n = 7). We did not detect a training effect on AV-nodal conduction intervals. His signals were present in 1 horse during 2AVB with varying H-V interval preceding a blocked beat. Conclusions and Clinical Importance: We identified decreased HR and increased frequency of 2AVB in trained horses. In 5 of 7 horses, His signal recordings had variable H-V intervals within each individual horse, providing novel insight into AV conduction in horses.

KW - athlete's heart

KW - atrioventricular conduction

KW - cardiac arrhythmia

KW - equine

KW - His signal

KW - sinus node recovery time

KW - specialized conduction system

UR - http://www.scopus.com/inward/record.url?scp=85129198700&partnerID=8YFLogxK

U2 - 10.1111/jvim.16427

DO - 10.1111/jvim.16427

M3 - Journal article

C2 - 35488721

AN - SCOPUS:85129198700

VL - 36

SP - 1119

EP - 1130

JO - Journal of Veterinary Internal Medicine

JF - Journal of Veterinary Internal Medicine

SN - 0891-6640

IS - 3

ER -