Feline Cardiomyopathies: tips and tricks - Animal Health ...
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Feline Cardiomyopathies:
tips and tricks
Jonathan Lichtenberger, DVM, MSc, DACVIM (Cardiology)
acvim.org
1 2
1. What are the different
cardiomyopathies in cats?
Cardiomyopathies: « diseases of myocardium associated
with cardiac dysfunction »
World Health Organization, 1995
3 4
Classification
Chetboul, TVIM 8th ed ACVIM consensus 2019
5 6
Hypertrophic
UCM
cardiomyopathy
10 %
In cats… DCM
10 %
• Most common cardiac disease in cats: 15% of
apparently healthy cats, up to 29% if older
HCM than 9 yrs
RCM 58 %
21 %
• Primary concentric hypertrophy of the LV
• Genetic in origin
Ferasin et al, J Feline Med Surg 2003) Courtesy of Dr. Alfonzo Lopez
7 8
Secondary LV hypertrophy
Restrictive cardiomyopathy
= HCM phenotype
• Endomyocardial or myocardial fibrosis
• Hyperthyroidism
• Normal myocardial thickness
• Systemic hypertension
• Atrial (often biatrial) enlargement
• Acromegaly (increased GH secretion)
• Infiltration (inflammatory, neoplastic)
9 10
Arrhythmogenic right
Dilated cardiomyopathy
ventricular cardiomyopathy
• Decreased systolic
function
• Decreased myocardial
thickness
Fibro-fatty
• Severe eccentric infiltration
Courtesy of Dr. Alfonzo Lopez hypertrophy (= dilation)
RV dilation
Primary DCM : rare +++
Secondary to taurine deficiency +++ (Pion et al, Science 1987) Can also affect
Fox P R et al. Circulation. 2000;102:1863-1870 the LV
11 12
2. What staging system do 2. What staging system do we
we use in cats ? use in feline cardiomyopathies ?
ACVIM consensus 2019
13 14
3. What are the possible Pathogenesis
complications of
Myocardial disarray +
cardiomyopathies ? fibrosis
Impaired relaxation and
compliance = diastolic
dysfunction + systolic
Arrhythmias dysfunction in advanced cases
Forward Heart Backward Heart
Syncope, sudden death
Failure Failure
15 16
4. What is the risk of developing
Other complication… complications in preclinical cats ?
http://maxshouse.com/arterial_thromboembolism.htm
http://www.vetnext.com
Aortic thromboembolism
Virchow’s triad
17 18
5. When should I suspect a
cardiomyopathy
• 1008 cats with HCM or HOCM were
followed for at least 5 years
• 5-year risk assessment (from study entry):
19.9% CHF, 9.7% ATE, 22.8% death
• 10-year risk assessment (from study
entry): 23.9% CHF, 11.3% ATE, 28.3% death
• No significant difference HCM vs HOCM
19 20
Clinical findings Clinical findings
• In symptomatic cats:
• In asymptomatic cats:
• Tachypnea/dyspnea
• Audible arrhythmia or gallop sound • Many cats have no auscultatory
• Heart murmur often no present
abnormality (esp RCM, DCM
phenotypes)
• Signs of ATE, 6P: paralysis, proprioception, pulseless,
pain, polar, palor • Heart murmur +/-
• RR > 80 brpm, gallop sound, T < 37.5°C, HR > 200 bpm
were most likely caused by CHF in cats with dyspnea • Gallop sound or arrhythmia ++
21 22
Clinical findings Clinical findings
• In asymptomatic cats:
• A loud heart murmur (3-4/6) is more common in
cats with HCM than in normal cats but there is a
lot of overlap
• A papable thrill (5-6/6) is most likely associated
with a congenital defect
• A change in murmur intensity does not
Payne et al, J Vet Cardiol 2015 n = 780 necessarily indicate a change in disease severity
23 24
6. How to diagnose 6. How to diagnose
subclinical cats? subclinical cats?
• Echocardiogram indicated if:
• Heart murmur
• Gallop
• Arrhythmia
• Patient considered at risk of CHF if undergoing
anesthesia, IV fluid therapy, extended-release
corticosteroids: older cats, breeds at risk (Maine coon,
Ragdoll, British Shorthair Persian, Sphynx, Norwegian
forest cat, Birmans
25 26
Echocardiography Echocardiography
HCM cat: LV wall > 5-6 mm, diffuse HCM cat: LV wall > 6 mm, asymmetrical
Boon J, WILEY-BLACKWELL 2011 Boon J, WILEY-BLACKWELL 2011
Right-parasternal
Right-parasternal long
Cardiology - AVC short axis Cardiology - AVC
axis 4-chamber view
Radiology - AVC transventricular view
27 28
Echocardiography Echocardiography
RCM: normal wall thickness, stiff ventricles,
Thrombus / spontaneous echo contrast (smoke) restrictive filling pattern
DCM: systolic dysfunction
Cardiology - AVC
29 30
Echocardiography Biomarkers
• High-risk cardiomyopathies:
★ LA dilation / poor LA function NT-proBNP (inactive metabolite of Brain Natriuretic Peptide
★ Depressed LV systolic function formation) produced in response to myocardial stretch
★ Thrombus / spontaneous echo contrast
★ Extreme hypertrophy Good ability to distinguish CHF from primary
respiratory disease
(Fox et al, J Vet Cardiol 2009)
• Other complicating factors:
if > 265 pmol/L Se = 90.2%, Sp = 87.9%
★ LVOT obstruction / SAM Healthy cats vs occult HCM
★ Myocardial infarction (Fox et al, J Vet Intern Med 2011)
★ Restrictive filling pattern If > 99 pmol/L Se = 70.8 %, Sp = 100%
Chetboul, TVIM 8th ed
31 32
Biomarkers Biomarkers
NT-proBNP as a screening tool
NT-proBNP SNAP test
• If normal: no or mild disease
(cannot exclude the presence of a
Cardiopet Idexx
cardiomyopathy!)
Healthy cats or mild HCM vs mod/severe HCM
• If abnormal: echo is indicated
(Machen et al, J Vet Cardiol 2014)
Se = 88.6 %, Sp = 81.3%
33 34
Biomarkers Thoracic radiographs
CTnI (high sensitivity) and CTnT: diagnostic and prognostic • Cardiac enlargement: not systematic (concentric
value but not that useful in clinical practice hypertrophy)
• Complications: pulmonary edema, pleural effusion
Valentine heart shape:
• 88% had a cardiomyopathy (HCM,
RCM or UCM)
• 29 % had biatrial enlargement
• Cannot predict underlying disease
or enlargement pattern
n = 41
Winter et al, J Feline Med Surg 2014
35 36
Etiologic diagnosis Etiologic diagnosis
Genetic testing:
In older cats
★ Hyperthyroidism
Maine Coon and Ragdoll
★ Systemic hypertension http://animalendocrine.blogspot.ca
Thyroid palpation
But remember…low and age-related penetrance
Does not mean HCM is present
T4
Courtesy of Dr. Erin Trageser
Helpful for breeders
BP measurement
Fundic exam Veterinary ophtalmology 2011
37 38
1999: autosomal dominant mode of transmission in the
Maine Coon breed
2005: a single mutation in the MyBPC3 is discovered
http://arcus.centerblog.net/rub-le-maine-coon-.html
Maron et al, JACC 2014
39 40Myosin-Binding Protein C mutation Myosin-Binding Protein C mutation - Ragdoll
Fries et al, J Vet Intern Med 2008
Meurs et al, Genomics 2007
★ Same gene
★ Different region (exon 23)
21
countries
Prevalence = 34%
http://fermun.org/mun_in_the_world.php
• 3 238 samples
• North America, Europe, Asia and Austraiia Mutations found Maine Coons and Ragdolls are restricted to
• 90 % heterozygous, penetrance is low these two breeds (Longeri et al, J Vet Intern Med 2013)
41 42
Sphynx
Other tests
?
ECG / Holter /
Event monitor
• Detection of ventricular and
supraventricular arrhythmias
http://animalspicwallpaper.com/sphynx-cat-wallpaper-for-desktop/
• AV block
Autosomal dominant mode of transmission
• Not sensitive to detect chamber
Chetboul et al, J Vet Cardiol 2012 enlargement
Silverman et al, J Feline Med Surg 2012
43 447. How to diagnose cats Thoracic radiographs
with dyspnea?
45 46
POC thoracic ultrasound
Biomarkers
NT-proBNP SNAP test
On blood or pleural fluid (diluted 1:1)
Cardiopet Idexx
47 48LA enlargement
49 50
8. How to treat subclinical
• Treat the underlying cause if present!
patients?
• Taurine deficiency 250-500 mg BID (very rare)
• Systemic hypertension: Amlodipine is the Tx of
choice
• Hyperthyroidism
51 52• Should we treat asymptomatic cats ?
★ B-blockers: Atenolol
Decreases the
Increased Anti-arrhythmic
obstruction • No significant difference in 5-year survival between treated
diastolic time effect gradient if HOCM
(n=42) and untreated cats (n=21)
53 54
• My personal preference Prevention of ATE
When risk factors are
Atenolol 6.25 mg bid if: present
LA dilation
- moderate or severe LVOT obstruction Smoke or thrombus
= ACVIM stage B2
- extreme hypertrophy
Warfarin (coumadin)
- caution if left atrial enlargement Aspirin Clopidogrel
- « easy to pill »
Anti-Vit K
Anti-platelet aggregation High risk of hemorrhage,
Lethal 10-15% des cas
55 569. How to treat cats with
Prevention of ATE CHF?
Clopidogrel
Aspirin
18.75 mg SID
5 mg/cat to 5mg/kg q72h
In some cases, anti Xa agents
such as rivaroxaban
57 58
Treatment of CHF Treatment of CHF
• Diuretics:
★ Acute: Furosemide 1-4 mg/kg IV (repeat 30 mins later
if no response) • O2 cage - quiet environment
★ Chronic: Furosemide 0.5-2 mg/kg SID to TID (staring • Thoracocentesis if pleural effusion (does not
at 1-2 mg/kg PO BID) respond as well to diuretics !)
★ Refractory case: spironolactone 1-2 mg/kg SID to BID.
But not well documented and facial excoriation is a
• Sedation Butorphanol 0.1-0.2 mg/kg PRN
side effect (Mc Donald et al, J Vet Intern Med 2008)
59 60Treatment of CHF
Prevention of ATE
• ACE-inhibitors: benazepril 0.5 mg/kg SID
Clopidogrel
• Should only be used when the animal is stable and Aspirin
18.75 mg SID
eating!
5 mg/cat to 5mg/kg q72h
• No convincing benefits in clinical and subclinical
feline patients
In some cases, anti Xa agents
such as rivaroxaban
61 62
Treatment of CHF Treatment of CHF
• Pimobendan: 0.25 mg/kg BID, no prospective data • Pimobendan:
n = 27 P = 0.024
MST
J Am Vet Med Assoc 2014
Pimo: 626 days
Control: 103 days
63 6410. How to treat cats with
Treatment of CHF ATE?
• Pimobendan:
My personal preference, use if
- systolic dysfunction
- advanced disease: very severe atrial enlargement, end-
stage HCM, restrictive physiology
- refractory CHF, hypotension, signs of poor perfusion
- No significant LVOT obstruction
65 66
11. How to deal with cats
Treatment of ATE that are difficult to pill?
• Analgesia
• Better prognosis if normothermic, only 1 limb affected,
absence of CHF
• Start LMWH or unfractionated heparin (250-375 IU/kg
IV initially followed by 150-250 IU/kg SC q6-8h) or anti
Xa inhibitor (rivaroxaban)
• If PO medication possible, give 75 mg of clopidogrel
ASAP (followed by 18.75 mg SID)
67 68• Prioritise medications THANK YOU
• 1. Furosemide 2. Clopidogrel 3. Pimobendan 4. ACEI
• Combine medications: empty space in pimo
capsules, use of gel capsules, positive
reenforcement
• Use compounded liquid medications at high
concentrations (20 mg/ml furosemide, 5 mg/ml
pimobendan, not a good idea for clopidogrel)
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