Page 644 - WSAVA2018
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 25-28 September, 2018 | Singapore
 Age group
    Pre-test likelihood of clinically significant heart disease (i.e. prevalence of HCM)
  Post-test likelihood of clinically significant heart disease
 Positive SNAP test
   Negative SNAP test
  6 - 12 months
 1 - 3 years
   3 - 9 years
 ≥ 9 years
  Pierce KV, Rush JE, Freeman LM et al (2017). Association between survival time and changes in NTproBNP in cats treated for congestive heart failure. Journal of Veterinary Internal Medicine 31 678-684
 Clinical context
   Cardiac troponin I (cTnI)
   Level of evidence
   Respiratory distress: determining cardiac from noncardiac causes
  Higher cTnI in cardiac disease, but significant overlap between groups limits clinical use
  Higher NTproBNP
in cardiac disease. Plasma: cut-off value around 200 pmol/L may be useful, sensitivity >85%, specificity 84-88%.
Pleural fluid can also be used; apparently more sensitively than plasma and negating requirement for a blood sample.
  High for both, NTproBNP more accurate
   Identification of cats with occult cardiomyopathy
 No specific studies; reported increase in cTnI for cats with subclinical heart disease
 Higher NTproBNP in cats with subclinical cardiomyopathy. Cut-off value around 100 pmol/L appears useful.
Higher concentrations associated with more severe disease,
but insensitive for determining which cats have mild disease.
A patient-side test with a cut-off at this level (“abnormal” result >100pmol/L) has been validated
in a screening population to determine cats with moderate to severe heart disease, likely to be clinically significant, but the test has not yet been validated in a general practice population of older, non-pedigree cats.
 Higher for NTproBNP
 Prognostic use in cardiomyopathy
   Higher cTnI in cats that dies because of cardiac disease vs. noncardiac death.
cTnI >0.7 ng/ml associated with a shorter survival time in HCM, independent of clinical size
or left atrial size, possibly reflecting severe ischaemia or infarction.
   Higher single NTproBNP measurement associated with reduced survival,
but not useful once presence of clinical signs or left atrial size are considered.
Reduced NTproBNP during hospitalisation (serial measurements; admit and discharge) was associated with a longer survival
time than cats where NTproBNP did not reduce significantly.
   High for both
  Table 2: How using the NTproBNP SNAP test may help you to assess likelihood of significant heart disease being present in cats with heart murmurs
As you can see from Table 2, using the NTproBNP SNAP test allows you to further refine the process of deciding which cats with a heart murmur are likely to require echocardiography. To expand upon an example of a middle aged female cat, with a grade II/VI systolic heart murmur:
· Around 30% of cats like this have disease. If you recommend echo to every cat like this, around 70% of the time there will be no heart disease that is sig- nificant to that cat. However, if you were to use the NTproBNP SNAP test, you could be more selective in which owners to recommend echocardiographic assessment.
· If the SNAP test were positive, this individual cat has a 67% chance of having heart disease. This is clearly not a perfect test for heart disease, but it does mean that there is now more than twice the likelihood of heart disease being present in this cat (probability was 30.1%, now is 67.1%).
· If the test were negative you could explain to the owner that there is around a 1/20 chance the cat has significant heart disease (5.7%). Echocardiography may be undertaken, but just under 19 out of 20 times the echo will not show clinically relevant cardiomy- opathy.
Clearly, the NTproBNP SNAP test should not be used to make decisions regarding treatment and prognosis, because it does not provide a certain diagnosis. However, it may be helpful in assessing need for, or urgency to, perform echocardiography.
References and further reading:
Borgeat K, Connolly DJ and Luis Fuentes V (2015). Cardiac biomarkers in cats. Journal of Veterinary Cardiology 17 S74-S86
Bijsmans ES, Jepson RE, Wheeler C et al (2017). Plasma N-terminal probrain natriuretic peptide, vascular endothelial growth factor and cardiac troponin I as novel biomarkers of hypertensive disease and target organ damage in cats. Journal of Veterinary Internal Medicine 31 650-660

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