Cardiac arrhythmias during intense exercise in Thoroughbred racehorses: frequency and association with subsequent race performance.
The frequency, characteristics, and relationship with performance of arrhythmias occurring during high-intensity exercise in Thoroughbred racehorses remain poorly understood.
Describe the frequency, characteristics, and association with subsequent race performance of arrhythmias occurring during intense exercise.
Seventy-one racehorses competing in races sanctioned by the Hong Kong Jockey Club.
Risk-based case-control study. Single-lead ECGs were recorded during high-intensity trials using wearable devices. Ectopic depolarizations identified during warm-up, maximal exercise, and fast and slow recovery were characterized by frequency and morphology. Horses with ECG recordings obtained before a race were included. Race performance was classified as poor (finishing in the last 3 positions) or good (finishing in the first 3 positions). Associations between ECG variables and race performance were assessed using odds ratios.
A total of 405 ECGs were recorded within 21 days before 1 or more race starts (82 poor- and 142 good-performance starts). Arrhythmias were detected in 73% and 81% of ECGs preceding good and poor performances, respectively. Ectopic beats during maximal exercise occurred in 57% of ECGs before good and in 70% before poor performances. The odds of performing poorly increased with each additional ectopic beat (odds ratio [OR], 1.15; 95% confidence interval [CI], 1.04-1.28; P = .01), and horses with any ectopic beat were nearly twice as likely to underperform (OR, 1.8; 95% CI, 0.86-3.81; P = .02).
Ectopic beats are common and adversely associated with athletic performance. Electrocardiographic monitoring during intense exertion might enable detection of clinically important arrhythmias.
Describe the frequency, characteristics, and association with subsequent race performance of arrhythmias occurring during intense exercise.
Seventy-one racehorses competing in races sanctioned by the Hong Kong Jockey Club.
Risk-based case-control study. Single-lead ECGs were recorded during high-intensity trials using wearable devices. Ectopic depolarizations identified during warm-up, maximal exercise, and fast and slow recovery were characterized by frequency and morphology. Horses with ECG recordings obtained before a race were included. Race performance was classified as poor (finishing in the last 3 positions) or good (finishing in the first 3 positions). Associations between ECG variables and race performance were assessed using odds ratios.
A total of 405 ECGs were recorded within 21 days before 1 or more race starts (82 poor- and 142 good-performance starts). Arrhythmias were detected in 73% and 81% of ECGs preceding good and poor performances, respectively. Ectopic beats during maximal exercise occurred in 57% of ECGs before good and in 70% before poor performances. The odds of performing poorly increased with each additional ectopic beat (odds ratio [OR], 1.15; 95% confidence interval [CI], 1.04-1.28; P = .01), and horses with any ectopic beat were nearly twice as likely to underperform (OR, 1.8; 95% CI, 0.86-3.81; P = .02).
Ectopic beats are common and adversely associated with athletic performance. Electrocardiographic monitoring during intense exertion might enable detection of clinically important arrhythmias.
Authors
van Erck-Westergren van Erck-Westergren, O'Connor O'Connor, Stewart Stewart, Dubois Dubois, Morton Morton, Hinchcliff Hinchcliff, Ter Woort Ter Woort
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