Effect of a single dose of pimobendan on right ventricular and right atrial function in 11 healthy cats

Objectives: The objective of this study was to investigate the effect of pimobendan on echocardiographic parameters of right ventricular and atrial function in healthy cats. Animals: Eleven privately owned, healthy adult cats. Material and methods: Each cat underwent five echocardiographic examinations: the first and second examinations were performed 1 h apart on day 0. On day 1, the third examination served as baseline, whereas the fourth and fifth examinations were performed one and 6 h after administration of a single oral dose of pimobendan (1.25 mg/cat), respectively. Parameters of right ventricular and atrial morphology and function were collected and compared among time points. Results: Pimobendan administration produced a change in some echocardiographic variables. Specifically, heart rate, right ventricular fractional shortening and peak velocity of systolic lateral tricuspid annular motion increased (P = 0.032, P = 0.002 and P < 0.001, respectively), whereas right ventricular end-systolic internal diameter and right atrial maximum and minimum internal diameters decreased (P = 0.004, P = 0.025 and P = 0.01, respectively). Right ventricular fractional area change and tricuspid annular plane systolic excursion did not change. Conclusions: This novel study showed that pimobendan had positive effects on right ventricular and right atrial function in healthy cats. Further studies are needed to determine whether pimobendan has similar effects in cats with cardiac diseases.