Clinical evaluation of a digital stethoscope with simultaneous phonocardiography and electrocardiography in cats

A smartphone-based technology combining a digital stethoscope (DS) with simultaneous phonocardiography (PCG) and 1-lead electrocardiogram (ECG) is available. The aim of the present study was to evaluate the sensitivity and specificity of the DS for the detection of heart disease in cats considering transthoracic echocardiography as gold standard. The study is prospective and observational inlcuding 42 client-owned cats. All cases underwent auscultation with a conventional stethoscope (CS), recording with the DS, 6-lead ECG and echocardiography. All the recordings were blindly reviewed. The agreement with standard methods was assessed using the Cohen's kappa and the Bland-Altman test. The Fisher's exact test was used to test the effect of shaving on tracings' quality. Intraoperator and interoperator variability were assessed with Cohen's k and Fleiss' k, respectively. Audio recordings obtained with DS were interpretable in 100% of the cats. The agreement between DS and echocardiography in detecting heart disease was substantial (k = 0.714), while between CS and echocardiography the agreement was moderate (k = 0.571). Intraoperator and interoperator agreement was almost perfect (k = 0.904; k = 0.867, respectively). The ECG tracings recorded with the DS were interpretable in 83% of the cats and the device was reliable in assessing basic ECG measurements. No significant differences were found in the quality of the audio and ECG tracings in relation to the shaving condition. Based on the efficacy of detecting cardiac murmurs and gallop sound, the DS can be considered a reliable tool for cardiac auscultation in cats, producing good quality audio and ECG tracings also suitable for possible remote interpretation.