Survival of dogs with myxomatous mitral valve disease administered preclinical pimobendan in comparison to pimobendan-naïve dogs from the onset of congestive heart failure.

INTRODUCTION/

OBJECTIVES

In the preclinical phase of myxomatous mitral valve disease, pimobendan administration to dogs with cardiomegaly reduces cardiac dimensions and risk of congestive heart failure (CHF). Administration of pimobendan to dogs with CHF prolongs survival. Increasing proportions of dogs are administered preclinical pimobendan; however, the influence of this on CHF survival time in dogs that progress to CHF has not been explored in a multicentre study.

ANIMALS, MATERIALS AND

METHODS

This is a multicentre retrospective study comparing survival time from the onset of CHF in 137 dogs from five centres administered preclinical pimobendan (B2P, n = 61, 44.5%) or 'pimobendan naïve' (B2N, n = 76, 55.5%) at the onset of CHF.

RESULTS

At the onset of CHF, there were no differences in patient, echocardiographic or biochemical variables between groups. Following the onset of CHF, median times to all-cause mortality and cardiac death were shorter in Group B2P than in Group B2N: 168 days (95% confidence interval: 58-227) vs. 359 days (245-473), P<0.001 and 201 days (128-287) vs. 442 days (293-711), P<0.001, respectively. There was no difference in proportions of dogs experiencing cardiac death between groups (P=0.116).

CONCLUSIONS

Whilst preclinical treatment of myxomatous mitral valve disease with pimobendan is anticipated to be the optimal management strategy in extending and maintaining quality of life overall, these results suggest that in dogs developing CHF, the survival times of dogs administered preclinical pimobendan might be shorter following the onset of CHF. Preclinical pimobendan administration should be considered when interpreting survival studies and when managing dogs that develop CHF.

STUDY LIMITATIONS: This is an underpowered retrospective study.