Background: Left ventricular (LV) systolic dysfunction is associated with a poor prognosis in cats with hypertrophic cardiomyopathy (HCM). Echocardiographic strain techniques are used in people to demonstrate regional wall motion abnormalities, but these techniques require optimal image quality and advanced software. We demonstrate the use of M-mode echocardiography to evaluate regional radial wall motion in cats. Hypothesis/
Objectives: In cats with HCM stage B2 and C, LV free wall (LVFW) systolic excursion (SE) is lower than septal SE. Animals: 75 client-owned cats, including 12 healthy cats and 63 cats with HCM (stage B1, n=24; stage B2, n=20 and stage C, n=19).
Methods: One observer reviewed right parasternal short-axis cineloops from our echocardiographic records. Healthy cats and cats with HCM with normal sinus rhythm and acceptable image quality were included. Left ventricular short-axis images at the papillary muscle level were divided into 3 septal and 3 LVFW myocardial segments. Anatomical M-mode was used for measuring the SE of each radial segment.
Results: Mean systolic excursion of all 6 segments was progressively lower comparing stage B1, B2 and stage C cats (P < 0.0001). In stage B2 cats the SE in the LVFW and septum were similar (P = 0.608), whereas stage C cats had lower SE in the LVFW (2.8mm ± 1.2mm) than the septum (4.0mm ± 1.3mm; P < 0.0083). Conclusions and Clinical Importance: Regional systolic dysfunction is present even in subclinical stages of HCM, and progressively worsens with advancing stage of HCM. This effect is more marked in the LVFW.
