Management of cats with cardiomyopathy Flashcards
What is the general consensus to start treatment for a cat with cardiomyopathy
The general consensus is that:
- any cat with mild to moderate myocardial hypertrophy (6-7 mm)
- with a normal to mildly enlarged left atrial size (< 16 mm diam)
- with no or mild LVOT obstruction
requires no therapy but should be monitored for evidence of disease progression
- ideally by repeat echocardiography every 6-12 months
What is the only treatment with unequivocal benefit in cats with signs of congestive heart failure
Loop diuretics
- the minimal effective dose should be used after an initial moderate to high dose is used
What is the indication for beta-blockers (e.g., atenolol)
Beta-blockers may be useful where tachycardia or dynamic left ventricular outflow tract obstruction is contributing to recurrent syncope or low cardiac output (as evidenced by a reluctance to play or exercise)
Typically, atenolol is started at a dose of 6.25 mg, PO, q12h and then titrated up to 12.5 mg if necessary to achieve a heart rate of 160-180 BPM in the exam room
Explain why beta-blockers should not be used in the presence of overt congestive heart failure (unless there is a hemodynamically significanttachyarrhythmia)
Beta-blockers should not be used in the presence of overt congestive heart failure due to their negative inotropic and chronotropic effects which may result in a fatal reduction in cardiac output
Which condition may make cats at risk when using beta-blockers in the management of a cardiomyopathy
Care should be taken in cats with a history of allergic airway disease due to the blockade of beta-2 receptots in the airways (with resultant bronchoconstriction) at higher doses
When would a treatment of systolic dysfunction be appropriate
It is appropriate to add a psoitive inotrope to the therapeutic regimen if evidence of systolic dysfunction is found on echocardiography
- fractional shortening < 28 %
- or ventricular internal diameter at the end of diastole > 11 mm
What positive inotropes can be used in cats
Digoxin at a dose of 0.0312 mg PO every 48 hours can be used
- toxicity may be a problem
- may be useful if concurrent atrial fibrillation is observed
- cats being treated with this drug should ideally have a heart rate of 140-160 BPM while at the clinic
Pimobendan is safe for use in cats at a dose of 1.25mg, PO, q12h
- it is a calcium sensitizer and a phosphodiesterase inhibitor that has a positive inotropic, lusitropic and vasodilatory effects
- the addition of pimobendan to traditional treatment for CHF may provide a substantial clinical benefit in survival time for HCM-affected cats with CHF and possibly HOCM-affected cats with CHF
What are poor prognosis indicators for cats with HCM
Presence of arrhythmia usually means that significant heart disease is likely
Arterial thromboembolism
Decreased LA and LV systolic function
LV hypertrophy of 9 mm or more
Cardiac troponin value of > 0.7 ng/ml at the time of diagnosis appears to be predictive of a shorter median survival time
