Abstract:
Background: Transient myocardial thickening (TMT) is a relatively recently d1escribed entity in feline cardiology
first introduced in 2018 by Novo Matos et al, characterized by reversible left ventricular wall thickening (LVWT) that
initially mimics hypertrophic cardiomyopathy (HCM). Recognition of TMT may have a significant impact on daily
clinical cardiology, as it can encourage both clinicians and owners to pursue treatment in cases that would traditionally
be considered to carry a poor prognosis, thereby reducing the risk of premature euthanasia. The aim of this study is to
present a case of TMT in a young cat and to illustrate the role of serial echocardiography.
Case description: A one-year-old male British Shorthair cat, was presented with acute dyspnea and lethargy. On
physical examination tachypnea, gallop rhythm, and systolic murmur were detected. Thoracic radiographs revealed the
presence of pulmonary edema and pleural effusion, and echocardiography showed marked concentric LVWT (IVSd:6.2
mm; LVPWd: 9.3 mm) with severe left atrium dilation and the presence of spontaneous echocardiographic contrast. The
cat was treated with furosemide, oxygen supplementation and anticoagulants. At re-evaluation three months later,
echocardiography showed complete normalization of left ventricular wall thickness with no evidence of persistent
hypertrophy, supporting the diagnosis of transient myocardial thickening rather than HCM. The cat remained clinically
stable during follow-up.
Conclusion: This case highlights the importance of recognizing transient myocardial thickening as a differential
diagnosis for hypertrophic cardiomyopathy phenotype in cats presenting with acute myocardial changes. Serial
echocardiographic assessment is essential for accurate diagnosis and prognosis, as TMT carries a more favorable longterm
outcome compared to HCM. Notably, this syndrome is most often reported in young cats and closely resembles
stress-induced cardiomyopathy described in humans, further underlining its clinical and comparative relevance.
