Resting and Dobutamine Stress Echocardiographic Factors Associated with the Development of Occult Dilated Cardiomyopathy in Healthy Doberman Pinscher Dogs

In 29 healthy Doberman Pinschers, echocardiographic parameters evaluating systolic and diastolic function were examined prospectively at rest and during dobutamine constant rate infusion (5 μg/kg/minute) to determine if any parameters were associated with the development of occult dilated cardiomyopathy (DCM). A resting echocardiogram was repeated 1 year later to determine which dogs had met our criteria for occult DCM. Six dogs developed occult DCM during the follow-up period. Univariate logistic regression analysis showed that at rest, an increased left ventricular internal dimension in systole (LVID-S) ( P = .02), preejection period (PEP) ( P = .03), ratio of PEP to left ventricular ejection time ( P = .02), and isovolumic relaxation time ( P = .02) were significantly associated with the development of occult DCM. During dobutamine stress echocardiography (DSE), high LVID-S ( P = .02) and systolic wall stress index ( P = .04) and reduced fractional shortening ( P = .02) and ratio of peak early to late diastolic mitral filling velocity (E/A) ( P = .05) were associated with the development of occult DCM. Multiple logistic regression showed that LVID-S ( P = .002) and E/A ( P = .002) measured during dobutamine infusion also were associated with the development of occult DCM. Reclassification based on the DSE data was not significantly different than reclassification based on the resting echocardiographic data. Resting echocardiography and DSE have the potential to be clinically applicable screening tests for very early systolic and diastolic dysfunction in Doberman Pinschers, heralding the onset of occult DCM as it is currently defined.