Assessment of plasma cardiac troponin I concentration as a means to differentiate cardiac and noncardiac causes of dyspnea in cats

OBJECTIVE: To determine whether plasma cardiac troponin I (cTnI) concentrations can be used to discriminate cardiac from noncardiac causes of dyspnea in cats. DESIGN: Prospective, multicenter study. ANIMALS: Client-owned cats with dyspnea attributable to congestive heart failure (D-CHF; n=31) or to noncardiac causes (D-NCC; n=12). PROCEDURES: For each cat, plasma cTnI concentration was analyzed by use of a solid-phase radial partition immunoassay; values in cats with D-CHF and D-NCC were compared. A receiver operating characteristic curve was analyzed to determine the accuracy of plasma cTnI concentration for diagnosis of D-CHF. RESULTS: Median plasma concentration of cTnI in cats with D-CHF (1.59 ng/mL; range, 0.20 to 30.24 ng/mL) was significantly higher than in cats with D-NCC (0.165 ng/mL; range, 0.01 to 1.42 ng/mL). With regard to the accuracy of plasma cTnI concentration for diagnosis of D-CHF, the area under the receiver operating characteristic curve was 0.84. At plasma concentrations > or = 0.2 ng/mL, cTnI had 100% sensitivity but only 58% specificity for identification of CHF as the cause of dyspnea. At plasma concentrations > or = 1.43 ng/mL, cTnI had 100% specificity and 58% sensitivity for identification of CHF as the cause of dyspnea. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of the derived diagnostic limits, CHF as the cause of dyspnea could be ruled in or ruled out without additional diagnostic testing in > 50% of the study cats. Measurement of plasma cTnI concentration may be clinically useful for differentiation of cardiac from noncardiac causes of dyspnea in cats. (J Am Vet