Left Atrial Function as an Early Indicator of Thromboembolic Risk in Cats with HCM

Hypertrophic cardiomyopathy (HCM) remains the most common heart disease diagnosed in cats, and one of its most serious complications is the development of thromboembolism. Identifying early warning signs of clot formation is a critical step in improving outcomes for feline patients.

A new preliminary study examined the relationship between spontaneous echocardiographic contrast (SEC) and left atrial (LA) structure and function in cats with HCM. SEC, often described as a swirling “smoke-like” pattern within the atrium on ultrasound, is considered a marker of increased thromboembolic risk.

Study design
The research team evaluated three groups of cats:

• Healthy controls (n = 8)

• Cats with HCM but no SEC (n = 12)

• Cats with HCM and SEC (n = 8)

Echocardiographic measurements included LA size, volume, and functional parameters such as left atrial shortening fraction (LAFS%) and left atrial fractional area change (LAFAC).

Results
Both LAFS% and LAFAC were significantly different among the groups. Cats with HCM and SEC demonstrated reduced atrial function compared to healthy cats and those with HCM without SEC. These findings suggest that impaired LA function may be present before SEC develops.

Clinical significance
The study highlights the potential value of monitoring LA functional parameters in addition to size and volume. Declines in LAFS% and LAFAC may serve as early indicators of thromboembolic risk in cats with HCM, supporting closer surveillance or earlier intervention.

Next steps
While the study was limited by its small sample size, the results provide a foundation for further investigation. Future research should focus on larger populations, including asymptomatic HCM cats, to establish clinically useful cut-off values for LAFS% and LAFAC.
This preliminary evidence reinforces the importance of comprehensive echocardiographic assessment in feline HCM. By evaluating left atrial function—not just size—veterinarians may gain a more accurate picture of thromboembolic risk and improve management strategies for cats living with this complex disease.

Read full study here: https://journals.pan.pl/dlibra/publication/151743/edition/132537/content