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

Abstract

OBJECTIVE: To determine if serum cardiac troponin I (cTnI) concentrations can distinguish cardiac from non-cardiac causes of respiratory distress (RD) in cats. ANIMALS, MATERIALS AND METHODS: 53 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). RESULTS: The 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 > or = 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. CONCLUSIONS: Serum 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.