pro-BNP in cats as a screening tool

Re: pro-BNP in cats as a screening tool

Rob Loxley — Thu, 16 May 2013 14:50:27 GMT

[quote user="Anthony Dennison"] the other thing to think about is that if a cat is going on fluids it is most likely to be a non-routine op and a grade 2-4 on the (New York?) anaesthetic classification scale, so will be a higher risk GA anyway. This could skew data slightly[/quote]

I believe the increased risk found with fluids was independent of age/procedure/health status as assessed

Re: pro-BNP in cats as a screening tool

David Mills — Thu, 16 May 2013 14:15:42 GMT

[quote user="Martin Atkinson"]but although you say many cats will not progress to CHF/ATE at least 1/3 of apparently healthy cats with murmurs will [/quote]

[quote user="Martin Atkinson"]Given also many don't progress to CHF but just drop dead without warning I have to give my clients the options.[/quote]

To me, these read like statements of fact. They are not, as I now realise, but rather your own personal experience. This is all that I was after.

[quote user="Martin Atkinson"] I'm not advocating what I've said as the definitive viewpoint I would just like others to benefit from my knowledge/experience[/quote]

If this is the case then what you write whilst giving others advice should be preceded with a caveat, otherwise it may be misinterpreted. The statements above are not even written in the first person. IME far far fewer than a third of cats develop clinically significant (i.e. showing established signs) heart disease, and very few 'drop dead' from having a murmur or other one minute to death the next.

If you want to base your practice on lizards in the sky, it really isn't any of my business. But if posting on a forum, I would try to make it clear - or at least answer an innocent query about the source straightforwardly - where what I said came from.

Re: pro-BNP in cats as a screening tool

Anthony Dennison — Thu, 16 May 2013 12:56:18 GMT

[quote user="robloxley"]

[quote user="John Flynn"]I thought I saw a survey in the past that showed a higher peri-anaesthetic mortality in cats associated with intravenous fluid use.[/quote]

Yes, David Brodbelt's. However the reasoning for the link is not entirely clear - overperfusion through not using infusion pumps, underlying cardiac disease etc., so I'm not sure I'd reject all rationale for periop IVFT in cats, just think harder maybe

[/quote]

This has been discussed on the forum somewhere recently too - the other thing to think about is that if a cat is going on fluids it is most likely to be a non-routine op and a grade 2-4 on the (New York?) anaesthetic classification scale, so will be a higher risk GA anyway. This could skew data slightly

Re: pro-BNP in cats as a screening tool

Martin Atkinson — Thu, 16 May 2013 11:21:40 GMT

[quote user="David Mills"]

I simply asked for references for your claims. Instead you give a defence of your study, and some tangental point about general practitioners full of "I"s

Specifically, where does the figure of a 1/3 of cats with cardiomyopathy will go into CHF/ATE come from?

I think we've established that your pre-emptive treatment of cats is not based on published evidence, general practitioner or otherwise.

[/quote] I have not got statistical evidence, it is from my experience as is my belief that pre-emptive treatment is of benefit but it is not based on just hot air. It is no good demanding evidence from published work if no-one has published the work. I doubt you have ever read the article I wrote in Vet Times on this. If you did and you tore it apart then that is your privilege. As I've said repeatedly you can take or leave it as you wish, I'm not advocating what I've said as the definitive viewpoint I would just like others to benefit from my knowledge/experience, they can then make their own decision, they don't need you to hold their hands over it. My clients are given all sides of the situation and given the option of a referral to a cardiologist so they can make up their own minds. The attitude that everything has to be based on peer reviewed, published, scrupulously prepared, scientific data before anyone can try something new deprives us all of a wealth of knowledge that is out there in general practice and makes others reluctant to discuss their experiences. You need to lighten up David and accept that some of us are not as dim as you seem to like to think, this is pathognomic of your attitude in most other threads, you seem to thrive on denigrating others and looking for negativity at every turn.

Re: pro-BNP in cats as a screening tool

David Mills — Thu, 16 May 2013 09:41:45 GMT

[quote user="Martin Atkinson"]I'm not being vitriolic just playing you at your own game David.[/quote]

This is starting to sound like a Tom Lonsdale defence I'm afraid. Who's playing games, exactly?

I simply asked for references for your claims. Instead you give a defence of your study, and some tangental point about general practitioners full of "I"s

Specifically, where does the figure of a 1/3 of cats with cardiomyopathy will go into CHF/ATE come from?

I think we've established that your pre-emptive treatment of cats is not based on published evidence, general practitioner or otherwise.

Re: pro-BNP in cats as a screening tool

ashvetenry — Thu, 16 May 2013 09:37:21 GMT

[quote user="Martin Atkinson"] Perhaps you could advise us what symptoms your cat had that led you to suspect cardiac disease and perform the test in the first place. Your cat may have been suffering from hypertension due to compensation for its anoxia and we know that BNP is released as a regulator of hypertension in cats with renal disease which is why it is raised in this condition. NT-proBNP is not telling you the cause of its elevation it is only being released from the ventricular myocytes in response to cardiac stress but coupled with other investigative techniques is a useful marker of cardiac disease. If it did nothing else it drew your attention to a potential problem and you did some additional investigation so it was still of value. It would be a shame if you dismissed it as a useful tool on the basis of this experience.

[/quote]

The cat presented with fairly acute onset repiratory distress late one evening- the history and clinical examination made me suspicious of asthma.

I injected the cat with dexamethasone and at re examination less than 24 hours was markedly improved. However on this occasion the heart rate was 220 (200 the previous day) and I could hear an intermittent but frequent gallop rhythm- the reason for running the proBNP. Full bloods inc proBNP were run. UREA was sl elev at 12, CREA was normal at 151 but globulins were elevated at 50.7 along with the very high proBNP. I still suspected asthma / inflammatory process following marked response to CCS and the globulin elevation, but given the very high proBNP after discussion with the owner opted for referral for scanning rather than furhter in house work up. It would indeed be nice to measure the proBNP value again- but the cat is not insured and is somewhat lost to follow up- I have phoned twice for an update (all is fine) but the cat has not been seen again by me or Mike.

Your comments do restore a little faith in the parameter for me however.

Re: pro-BNP in cats as a screening tool

David Mills — Thu, 16 May 2013 09:27:03 GMT

[quote user="ashvetenry"]

I have limited experience of using NT-proBNP but my most recent, and last as a result of the result was a cat with a value of 919 from Idexx. A caridac ultrasound scan was performed by Mike Martin and was completely normal. The cat was ultimatley diagnosed with marked narrowing of the rima glottis due to oedematous swelling of the surrounding laryngeal mucosa with some inflammation which responded completely to corticosteroids.

This was then a vey high and misleading false positive.

[/quote]

Not uncommon, this, actually. Specificity of the test has never exceeded 88% in peer-reviewed studies, meaning, in practical terms, 12 in every hundred positives will be a false positive. Two of these studies used cats with dyspnoea, so this is not a function of population prevalence, and it is a circumstance where the test is supposed to function at its most optimal. Therefore in the wider healthy population it is very likely to perform more poorly. In the dyspnoeic, it may well lead - if used without echo/imaging - to incorrect treatment. There is also a time lag of 12-24h before a result is obtained. Compare this to a 5s echo estimation of LA size in a dyspnoeic animal.

Re: pro-BNP in cats as a screening tool

Rob Loxley — Wed, 15 May 2013 23:48:15 GMT

[quote user="John Flynn"]I thought I saw a survey in the past that showed a higher peri-anaesthetic mortality in cats associated with intravenous fluid use.[/quote]

Re: pro-BNP in cats as a screening tool

John Flynn — Wed, 15 May 2013 20:03:09 GMT

[quote user="robloxley"]

[quote user="Sarah Keir"]As a practice, we routinely recommend intravenous fluids for dogs/cats over 10years old[/quote]

Is the evidence base for this any better than screening liver and kidney parameters in older pets - or proBNP for that matter.

[/quote]

I thought I saw a survey in the past that showed a higher peri-anaesthetic mortality in cats associated with intravenous fluid use.

I would separate out cats and dogs here, perhaps just stick to pros / cons of this policy in cats first?

Re: pro-BNP in cats as a screening tool

Rob Loxley — Wed, 15 May 2013 19:51:47 GMT

[quote user="Sarah Keir"]As a practice, we routinely recommend intravenous fluids for dogs/cats over 10years old[/quote]

Is the evidence base for this any better than screening liver and kidney parameters in older pets - or proBNP for that matter.

Re: pro-BNP in cats as a screening tool

Mark Hedberg — Wed, 15 May 2013 18:38:08 GMT

[quote user="ashvetenry"]

[quote user="Mark Hedberg"] Idexx's ranges for interpretation are fairly reliable, however, in the course of my investigations I have found that no cats showed symptoms of cardiac failure with an NT-proBNP of less than 350pmmol/l but all above that did and the severity of symptoms was in fairly direct proportion to levels found. I would therefore recommend some sort of pre-emptive treatment for all cats with a level > 270 (Idexx's upper limit of normal cats) and would say it is imperative above 350.

[/quote]

This was then a vey high and misleading false positive.

[/quote]

Just to clarify, that was Martin Atkinson saying that, not me - you've got the quote tags a little off!

Re: pro-BNP in cats as a screening tool

Martin Atkinson — Wed, 15 May 2013 18:13:40 GMT

[quote user="ashvetenry"]last as a result of the result was a cat with a value of 919 from Idexx. A caridac ultrasound scan was performed by Mike Martin and was completely normal. [/quote] I have experience of a cat with a murmur with a high NT-proBNP (upper 300's not as high as yours) which was sent for echo (not Mike Martin I hasten to add) and the result was normal. I respectfully requested that the record of the echo be reviewed and low and behold they changed their minds and decided it did have thickened left ventricle after all. I've had just one cat with a spuriously high NT-proBNP without (diagnosed) cardiac disease from an apparently unrelated inflammatory cause.The only other cases I've had where the NT-proBNP has been raised higher than expected in cats with or without cardiac disease was those with chronic renal failure and then it didn't raise it enough to make me doubt the value of the test. It would be interesting to re-check the values now the cat has recovered ash. Perhaps you could advise us what symptoms your cat had that led you to suspect cardiac disease and perform the test in the first place. Your cat may have been suffering from hypertension due to compensation for its anoxia and we know that BNP is released as a regulator of hypertension in cats with renal disease which is why it is raised in this condition. NT-proBNP is not telling you the cause of its elevation it is only being released from the ventricular myocytes in response to cardiac stress but coupled with other investigative techniques is a useful marker of cardiac disease. If it did nothing else it drew your attention to a potential problem and you did some additional investigation so it was still of value. It would be a shame if you dismissed it as a useful tool on the basis of this experience.

Re: pro-BNP in cats as a screening tool

ashvetenry — Wed, 15 May 2013 17:25:18 GMT

[/quote]

This was then a vey high and misleading false positive.

Re: pro-BNP in cats as a screening tool

Sarah Keir — Wed, 15 May 2013 16:45:42 GMT

[quote user="John Flynn"]

So I can see the logic in testing then if I'm going to be sedating or anaesthetising the cat; I'm not sure how significantly occult cardiomyopathy would change my protocols for these, but I'd be interested to learn.

[/quote]

As a practice, we routinely recommend intravenous fluids for dogs/cats over 10years old - what if these have occult cardiac disease? I have seen chests fill with fluid within a couple of hours of 2x maintence fluids. And what about the times when don't have time to do assessments such as these (pro-BNP or echo) in an emergency situation?

Re: pro-BNP in cats as a screening tool

Sarah Keir — Wed, 15 May 2013 16:42:52 GMT

[quote user="Mark Hedberg"]

[quote user="David Mills"]

[quote user="Mark Hedberg"]weight loss options, which would reduce load on the heart and surely improve prognosis[/quote]

Supposition. There is no basis for this whatsoever.

[/quote]

So obesity has no effect on the circulatory system, and has no long term effects on survivability?

[/quote]

What about the inflammatory effects of obesity? I am sure taht is anyone of us when to the GP with a heart condition and excess weight , their first recommendation would be to lose the love handles! I know we should anthropomorphise but surely obesity can't be good if there is a heart problem?

Re: pro-BNP in cats as a screening tool

Martin Atkinson — Wed, 15 May 2013 16:34:26 GMT

[quote user="David Mills"]

I simply asked for some references for some pretty bold claims you made. I note you haven't provided any. No need to invoke an ad hominem logic fallacy attack now is there?

Anecdote is all well and good. I'm sure there are many good vets who use such, with success.

[/quote]I'm not being vitriolic just playing you at your own game David. I wrote an article in Vet Times on NT-proBNP in cats and while it was generally accepted well for what it was by the average practitioner some pedants held it up for ridicule because it was not a peer reviewed, scientifically formulated and fully researched paper. The point is that I don't have the time nor indeed the inclination to gather evidence to write such a paper and fortunately I don't get put off by negative reviews so i will continue to try and share my experience. You can choose to take it or leave it, quite frankly my dear I don't give a damn, But there may be many out there who have a lot of experience to share but are not as tough skinned as me and are scared to do so because of just this attitude. As said it is not fair to compare this sort of anecdotal evidence to homoeopathy or even RMB, I am prepared to listen to the alternative point of view but it is based on some evidence it is not just purveying snake oil.

Re: pro-BNP in cats as a screening tool

John Flynn — Wed, 15 May 2013 08:17:25 GMT

[quote user="David Mills"]Common sense? The last resort of the no true Scotsman/special pleading logical fallacy.[/quote]

I thought the philosophical Scotsman was well known for their "School of Common Sense"

Re: pro-BNP in cats as a screening tool

David Mills — Tue, 14 May 2013 21:57:23 GMT

[quote user="Martin Atkinson"]

[quote user="David Mills"]

I'm not aware of any cat-specific studies that show this to be a clinically significant effect, or to reduce long term cardiac longevity. Are you?

Remember we're talking about only cardiac here.

[/quote]At what point David do you a) cease to play Devils Advocate; b) demand clinical trials for every conceivable situation c) accept that there is a lot of anecdotal evidence gathered by good vets in practice which will never be published; d) use your common sense. Not necessarily in that order!

[/quote]

Now now. I simply asked for some references for some pretty bold claims you made. I note you haven't provided any. No need to invoke an ad hominem logic fallacy attack now is there?

Anecdote is all well and good. I'm sure there are many good vets who use such, with success. But I don't know you, or them, I don't know what their decisions are based on. EBM allows us to converse on a level playing field; anecdote is the lowest level of evidence, by definition, because no one else can reliably assess its veracity. In fact, most studies into anecdote show an awful correlation with what clinicians think is successful reasoning/therapy and what the reality is - people naturally remember successes, awful failures and forget the vast majority of averages in between. People who react with vitriol to their personal paradigm being questioned, as you have, quite simply give the impression of well, untruth.

Common sense? The last resort of the no true Scotsman/special pleading logical fallacy.

Re: pro-BNP in cats as a screening tool

mariette asselbergs — Tue, 14 May 2013 16:30:55 GMT

Oops, sorry, had not read of of this thread yet.

Mariette

Re: pro-BNP in cats as a screening tool

mariette asselbergs — Tue, 14 May 2013 16:26:52 GMT

"I agree that there are no pharmaceutical interventions that are proven to be helpful in a cat with occult cardiomyopathy." (Graham)

Is it useful to advise these cats (and any cat with a heart murmur) to take aspirin e.g. 50 mg twice weekly for life? Or cartrophen maybe?

Mariette

Re: pro-BNP in cats as a screening tool

Martin Atkinson — Tue, 14 May 2013 09:56:19 GMT

[quote user="David Mills"]

I'm not aware of any cat-specific studies that show this to be a clinically significant effect, or to reduce long term cardiac longevity. Are you?

Remember we're talking about only cardiac here.

Re: pro-BNP in cats as a screening tool

Mark Hedberg — Mon, 13 May 2013 22:41:40 GMT

[quote user="David Mills"]

[quote user="Mark Hedberg"]So obesity has no effect on the circulatory system, and has no long term effects on survivability?[/quote]

I'm not aware of any cat-specific studies that show this to be a clinically significant effect, or to reduce long term cardiac longevity. Are you?

Remember we're talking about only cardiac here.

[/quote]

No, you're right, I should have specified that I was working anecdotally, and working on no paper-based evidence. Informally I've noticed fat dogs with heart disease seem to do clinically better after weight loss, but was merely making a logic-based guess on what effect this might have on cats. No papers on this, quite right.

Still, if it might have a positive effect on feline health, why not? Obesity isn't scientifically proven to be a health benefit, is it?

Re: pro-BNP in cats as a screening tool

David Mills — Mon, 13 May 2013 22:26:58 GMT

[quote user="John Flynn"]

I thought there was a reasonable paper behind the fad a number of years back of using low-doses of aspirin to reduce PTE in dogs being treated for IMHA.

I'm not saying I do this personally, and I suspect the paper will be pretty flawed (like the ones promoting spironolactone in dogs IMO),, but probably the closest to a demonstration of a benefit of aspirin in a subset of animals I'm aware of.

[/quote]

There was, but as you say its pretty deeply, and I think catastrophically flawed.

Possibly the best evidential review is this paper

http://www.ncbi.nlm.nih.gov/pubmed/23356703

which highlights the lack of clinically relevant, robust studies for any of the anti-thrombotics (in this case in terms of IMHA). Yes, experimental animals have shown surrogate endpoint benefits but no proof exists of increased survival.

Re: pro-BNP in cats as a screening tool

David Mills — Mon, 13 May 2013 22:21:38 GMT

[quote user="Mark Hedberg"]So obesity has no effect on the circulatory system, and has no long term effects on survivability?[/quote]

I'm not aware of any cat-specific studies that show this to be a clinically significant effect, or to reduce long term cardiac longevity. Are you?

Remember we're talking about only cardiac here.

Re: pro-BNP in cats as a screening tool

Mark Hedberg — Mon, 13 May 2013 21:24:09 GMT

[quote user="David Mills"]

[quote user="Mark Hedberg"]weight loss options, which would reduce load on the heart and surely improve prognosis[/quote]

Supposition. There is no basis for this whatsoever.

[/quote]

So obesity has no effect on the circulatory system, and has no long term effects on survivability?