Early detection of myocardial dysfunction using two-dimensional speckle tracking echocardiography in a young cat with hypertrophic cardiomyopathy

Abstract

Case summary: A 5-month-old intact female Scottish Fold cat was presented for cardiac evaluation. Careful auscultation detected a slight systolic murmur (Levine I/VI). The findings of electrocardiography, thoracic radiography, non-invasive blood pressure measurements and conventional echocardiographic studies were unremarkable. However, two-dimensional speckle tracking echocardiography revealed abnormalities in myocardial deformations, including decreased early-to-late diastolic strain rate ratios in longitudinal, radial and circumferential directions, and deteriorated segmental systolic longitudinal strain. At the follow-up examinations, the cat exhibited echocardiographic left ventricular hypertrophy and was diagnosed with hypertrophic cardiomyopathy using conventional echocardiography.

Relevance and novel information: This is the first report on the use of two-dimensional speckle tracking echocardiography for the early detection of myocardial dysfunction in a cat with hypertrophic cardiomyopathy; the myocardial dysfunction was detected before the development of hypertrophy. The findings from this case suggest that two-dimensional speckle tracking echocardiography can be useful for myocardial assessment when conventional echocardiographic and Doppler findings are ambiguous.

Figure 1

(a) Time-longitudinal global (dotted line) and segmental (coloured lines) longitudinal strain curve obtained from two-dimensional speckle tracking echocardiography (2D-STE; left apical four-chamber view) on day 0 in a young cat with hypertrophic cardiomyopathy (HCM). Six segmental curves are designated as the basal septum (yellow), middle septum (light blue), apical septum (green), apical lateral (purple), middle lateral (dark blue) and basal lateral (red) for speckle tracking analysis. Post-systolic shortening during the diastolic phase (arrow) can be observed. Note the lower and non-synchronous segmental strains (yellow and light-blue lines) corresponding to gradually hypertrophied segments on follow-up examinations (interventricular septum walls). All wall thicknesses on day 0, including the subaortic interventricular septum wall thickness on a long-axis view, were <6 mm, indicating the absence of left ventricular hypertrophy. (b) Time-longitudinal global (dotted line) and segmental (coloured lines, same as designated as above) longitudinal strain rate curve obtained from 2D-STE (left apical four-chamber view) on day 0 in a young cat with HCM. Note the small peak of systolic (S) and early diastolic (E) strain rate values. Global longitudinal strain rate E:A was 1.1. Conventional 2D and Doppler echocardiography did not reveal any sign of HCM on day 0. (c) Time-longitudinal global (dotted line) and segmental (coloured lines, same designated as above) longitudinal strain curve obtained from 2D-STE (left apical four-chamber view) for a healthy cat. Note the synchronous strains. (d) Time-longitudinal global (dotted line) and segmental (coloured lines, same designated as above) longitudinal strain rate curve obtained from 2D-STE (left apical four-chamber view) for a healthy cat. Note the strain rate E:A ratio of 1.9