Evaluation of cardiac arrhythmias in horses

Electrocardiogram abnormalities are common in racehorses and can have effect on performance. The aim of the study is to analyze the Electrocardiographic problem results and measure frequencies of various cardiac arrhythmias. The study was conducted during a period between September 2023 to August 2024, Standard electrocardiographic recordings were obtained from all horses, hematology, biochemical and cardiac troponin levels were measured. Out of the 114 poorly performing adult horses 40 cases without arrhythmia considered as a control group. Seventy-four horses (64.9%) had at least one type of cardiac arrhythmia, atrial fibrillation was observed in 60 cases (52.63%), and 29 horses (25.44%) had left axis deviation and left ventricular hypertrophy. The most frequent conduction anomaly was atrioventricular block in 34 cases (29.82%), followed by QT prolongation in 54 horses (47.36%), and QTc prolongation was seen in 50 horses (43.85%). Bradycardia was detected in 20 cases (17.54%), and ST-segment depression was present in 25 horses (21.93%). Conduction disturbances, including left bundle branch block in 13 horses (11.40%) and right bundle branch block in 26 horses (22.81%). Troponin levels were significantly elevated in cases of arrhythmia. The incidence of atrial fibrillation was significantly higher in male horses in all age groups except the oldest. Because cardiac arrhythmia may lead to racehorse exercise intolerance, suboptimal performance, the early diagnosis is important to allow veterinarians to make long-term treatment strategies, furthermore, the electrocardiography, along with cardiac biomarker cardiac troponin, is essential.