Assessment of the diagnostic accuracy of circulating cardiac troponin I concentration to distinguish between cats with cardiac and non-cardiac causes of respiratory distress

ObjectiveTo determine if serum cardiac troponin I (cTnI) concentrations can distinguish cardiac from non-cardiac causes of respiratory distress (RD) in cats.Animals, materials and methods53 cats. cTnI concentrations were measured in 30 cats with non-cardiac respiratory distress (RD-NC) and compared to 23 cats with RD due to congestive heart failure (RD + CHF).ResultsThe RD + CHF group had higher median cTnI concentration (0.94 ng/ml interquartile range IQR 0.54–4.00, range <0.20 – 90.14) than the RD-NC group (<0.2 ng/ml IQR < 0.2–0.33, range <0.20–41.1, p < 0.001). The area under the curve (AUC) was 0.842 (95% CI 0.728–0.955) for the receiver operator curve (ROC) analysis of the accuracy of cTnI concentrations to discriminate RD + CHF from RD-NC cats. A cut-off of ≥ 0.81 ng/ml discriminated RD + CHF from RD-NC cats with a sensitivity and specificity of 65.2% and 90.0% respectively. However considerable overlap in cTnI concentrations between the 2 groups was identified.ConclusionsSerum cTnI concentrations were different in RD + CHF compared to RD-NC cats. However the overlap in cTnI concentrations between the 2 groups reduced the clinical efficacy of the assay which therefore should not be used as a stand-alone test but in combination with other diagnostics such as echocardiography and radiography.