Resolution of dynamic left ventricular outflow tract obstruction and reversible left ventricular hypertrophy in 4 cats.

This case series describes spontaneous resolution of systolic anterior motion of the mitral valve, cessation of a dynamic left ventricular outflow tract obstruction, and reverse cardiac remodeling in 4 young cats. Following initial presentation with or without congestive heart failure, subsequent rechecks documented resolution of systolic anterior motion of the mitral valve and normalization of left heart dimensions. Those cats originally presented with congestive heart failure were successfully weaned off diuretic medications. Atenolol was prescribed to all 4 cats, and all remained on oral atenolol through the final recheck. There was no documented recurrence of progressive heart disease and heart failure in any of the cats. Consideration is given to transient myocardial thickening, spontaneous resolution of mitral valve dysplasia, and response to beta-1 adrenergic antagonism as possible underlying mechanisms. Key clinical message: When presented with young cats with hypertrophic obstructive cardiomyopathy, veterinarians should consider multiple differential diagnoses, as lifespan in these cases may be longer than typically expected for cats with primary hypertrophic cardiomyopathy, even with concurrent congestive heart failure.