Is treatment with pimobendan associated with an increased risk of arrhythmias in dogs with heart disease? DOGS

Pimobendan is a positive inotrope and balanced vasodilator via its actions as a calcium sensitiser and phosphodiesterase III inhibitor, respectively.1 There is strong evidence for its use in the treatment of dogs with congestive heart failure (CHF), with multiple clinical trials demonstrating a resultant increase in survival time.2-5 However, the use of pimobendan for treatment of heart disease in people has been associated with increased risk of arrhythmias.6 This effect is attributed to the racemic nature of pimobendan resulting in D and L chiral enantiomers, with the L-optical isomer having a significantly greater calcium sensitising effect.7-9 There is limited data available regarding any effect of treatment with pimobendan on the risk of arrhythmias in dogs. The aim of this article is to analyse the available data to determine whether evidenced-based conclusions can be drawn.