RE: Heart murmur 11.5 Yr old FN cat

louise Farrington — Fri, 16 Oct 2020 19:03:40 GMT

Hi Chris

Thank you so much for all this information, I was posting on behalf of a colleague and have checked hx and it was a snap test so results probably even less helpful! I will however, pass on the information to them and hopefully we can do something which will help.

Thanks again

RE: Heart murmur 11.5 Yr old FN cat

Chris Linney — Fri, 16 Oct 2020 10:39:23 GMT

Hi Louise,

It sounds as though there are no clinical signs, only the murmur on auscultation and pruritus.

Was the BNP a SNAP test or a quantitative one with a numerical value? The NTproBNP probably suggests that there is underlying heart disease, but in the absence of clinical signs, it becomes less valuable. A positive test in a tachypnoeic cat would help increase suspicion of clinically significant heart disease. The value of the positive result here in your case doesn’t completely help with the treatment decision.

There would be two aspects on this case:

First - the risk of heart failure. There are not any treatments recommended at this time to delay or prevent CHF. Given the high NTproBNP there is a risk of developing CHF if there is significant, advanced heart disease. I would ordinarily ask the clients to monitor the resting respiratory rate and effort at home, pre- and during steroid therapy. But I would not consider diuretics if respiratory rate is normal.

Second - the risk of thromboembolic disease. The NTproBNP is elevated there is likely to be increased wall stress (need to bear in mind the ~15% rate of false positive results). We do not know left atrial size, so it is difficult to know if thromboprophylaxis could be beneficial. An elevated NTproBNP alone would not usually prompt treatment for me. We have no good evidence to support using primary thromboprophylaxis (unlike secondary treatment following an ATE event). However despite this, where there is left atrial dilatation, along with some other echo indices, I would start clopidogrel. There is a flavoured version available from BOVA now which could be easier for the client to administer where the tablet form has been a bitter pill to swallow.

The latest ACVIM Consensus of Diagnosis and Treatment of Feline Cardiomyopathy is worth a review, there is a section on NTproBNP, but in the consensus they do not recommend using NTproBNP in asymptomatic animals to guide therapy. In your case, where there is an elevation in NTproBNP, and steroids will be started for skin disease, on balance, I would consider clopidogrel. The missing piece is the left atrial size, but if I had to go without it, I think the likelihood of adverse events to clopidogrel (other than administering the actual treatment), I consider low enough to warrant starting.

Hope that is useful - I think it always tricky and the guidance would recommend decision making based on atrial size ideally!

Best wishes,

Chris