Preliminary assessment of left ventricular function by tissue Doppler imaging and two-dimensional speckle tracking echocardiography in horses with equine metabolic syndrome

The equine metabolic syndrome (EMS) has many parallels to the human metabolic syndrome (HMS). The HMS predisposes to cardiovascular diseases. Standard echocardiographic exams showed few abnormalities in HMS and advanced echocardiographic techniques are needed to detect altered cardiac function. Few studies have investigated cardiac function in horses with EMS. As the pathomechanism of HMS and EMS are similar, the objective of the study was to determine whether horses with EMS have altered cardiac function assessed by tissue Doppler imaging (TDI) and two- dimensional speckle tracking (2DST) echocardiography. TDI and 2DST were performed in horses with confirmed EMS. The severity of the EMS was assessed with an EMS score and by the severity of insulin resistance (IR). Scores, age, bodyweight (BWT), height at the withers were compared among groups by parametric or non-parametric t-tests or ANOVAs with correction for multiple comparison. All 32 horses included showed a phenotype of EMS and IR. The study revealed no changes in the systolic left ventricular (LV) function. Concerning the diastolic LV function, late diastolic myocardial velocity (p = 0.012) and the early to late diastolic myocardial velocity ratio (p = 0.001) differed among age groups. However, no difference in the diastolic LV function could be shown between the EMS score or IR groups. In conclusion the diastolic LV function was reduced with age. However, the severity of clinical signs of EMS or the severity of IR do not seem to contribute to any variation in the LV systolic or diastolic function. However, larger studies will be needed to confirm our results.