Page 154 - Feline Cardiology

Table 11.1. Decision process for treatment of asymptomatic cats with HCM using beta blockers*
Medication Argument for the Use Argument against the Use
Considerations

↓Systolic anterior Dramatic reduction in the left ventricular to Indoor cats are sedentary animals that may not
motion (SAM) of aortic pressure gradient is possible in cats have high sympathetic tone until a stressor such
the mitral valve with moderate or severe SAM, which may ↓ as a trip to the veterinary office, which magnifies
severity of concentric LV hypertrophy the severity of the SAM far beyond what is seen
at home
By decreasing SAM, mitral regurgitation (MR)
is decreased, which may ↓ left atrial volume No information is available to confirm whether
overload and left atrial pressure in cats with reduction of SAM leads to improved quality of
moderate MR due to SAM life, survival, or delays onset of clinical signs

Some cats with moderate to severe SAM
have unrecognized symptoms until they are
treated, and then the owner observes Cardiomyopathies
symptomatic benefit including increased
energy and playfulness

↓ LV concentric Some cats receiving atenolol may experience No information regarding effect on morbidity,
hypertrophy reduction in severity of LV concentric mortality, or time to onset of clinical signs
hypertrophy The reduction in LV hypertrophy appears to be
relatively small in a placebo-controlled
↓ LV hypertrophy may improve diastolic prospective study
filling properties of the myocardium (i.e., ↓
stiffness), ↓ diastolic filling pressures and Some cats have improvement in LV hypertrophy
lessen risk of congestive heart failure without treatment or their hypertrophy never
worsens over many years, making the role of
medication questionable

Suppression of Acute stressful events may cause sinus Indoor cats may not have many acute stressful
tachycardia tachycardia, ↑ diastolic filling pressure, and events that could cause this phenomenon, aside
acute development of congestive heart from visits to the veterinary hospital, which likely
failure in cats, so blunting this acute would be increased during initial monitoring of
tachycardic response may be protective the cat receiving medications
Potentially similar effect can be achieved without
medication, by instructing owners to avoid
situations causing vigorous activity for the cat
(e.g., play with laser pointer, feather toys;
minimizing or avoiding outdoor roaming, etc.)

Effects on ↓ Heart rate will ↑ diastolic filling time, Beta blockers prolong early diastolic relaxation
diastolic function which may be beneficial in cats with stiff (negative lusitrope), which impairs early diastolic
hypertrophied ventricles by lessening function
diastolic filling pressures occurring during
tachycardia

↑ Myocardial stiffness is likely a more
important determinant of ↑ diastolic filling
pressure in cats than early diastolic
relaxation because cats have high heart rates
compared to other species, which minimizes
the overall negative impact of beta blockers
effects on slowing diastolic relaxation
(Continued)

153