Cardiac troponin I and the occurrence of cardiac arrhythmias in horses with experimentally induced endotoxaemia

The aim of this study was to determine whether experimentally-induced endotoxaemia induced elevations in plasma cardiac troponin I (cTnI) concentrations in horses and how this might affect the incidence of cardiac arrhythmias. Eight Standardbred horses received an intravenous continuous rate infusion of endotoxin (total dose 500 ng/kg) for 6 h while being monitored using electrocardiography (ECG). Blood samples were collected before the start of the endotoxin infusion, every 60 min during the infusion, then 1, 2, 3, 8, 10 and 24 h post-infusion, and analysed for cTnI concentrations. One horse was excluded from the study owing to a high initial cTnI concentration.Endotoxin infusion induced an increase in cTnI concentrations in all horses, reaching mean peak concentration of 0.135 ± 0.094 μg/L by 1 h post-infusion. The cTnI concentrations then decreased and were no longer significantly different from pre-infusion concentrations at 6, 10 and 24 h post-infusion. The number of ventricular events was generally low during the infusion period, but increased during the first 3 h post-infusion in 6/7 horses. In conclusion, elevated cTnI concentrations could be detected early after an endotoxaemic insult using an ultrasensitive cTnI assay, with peak cTnI concentrations preceding the occurrence of ventricular events on ECG.