Impaired left ventricular systolic function assessed by endocardial global longitudinal strain imaging in cats with restrictive cardiomyopathy.

Cats with RCM have significant systolic dysfunction detectable via GLS, beyond the classical diastolic impairment.

This retrospective case-control study investigated systolic function in cats with restrictive cardiomyopathy (RCM), the second most common feline cardiomyopathy, traditionally characterized by primary diastolic dysfunction. Twenty-five cats diagnosed with RCM were compared to 25 healthy age- and weight-matched control cats using two-dimensional speckle-tracking echocardiography (2D-STE) to derive endocardial global longitudinal strain (GLS) from left apical two-, three-, and four-chamber views. Cats with RCM demonstrated significantly larger left ventricular internal diameters in both systole (11.05 ± 2.24 mm vs. 8.48 ± 1.35 mm; P < 0.0001) and diastole (16.10 mm vs. 14.90 mm; P = 0.0015) compared to controls. Most critically, GLS values were significantly reduced in RCM cats (-17.68% ± 4.78) versus healthy controls (-28.35% ± 3.72; P < 0.0001), indicating impaired myocardial deformation and subclinical systolic dysfunction despite preserved or borderline conventional echocardiographic systolic indices. Study limitations include its retrospective design, absence of treatment standardization, lack of histopathological confirmation of RCM, and a relatively small sample size. These findings challenge the traditional view of RCM as a purely diastolic disease and suggest that 2D-STE-derived GLS may be a valuable tool for detecting concurrent systolic dysfunction in feline RCM patients. Clinicians should consider incorporating speckle-tracking echocardiography into cardiac assessments of RCM cats, as occult systolic impairment may influence prognosis and therapeutic decision-making.

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