Left atrial dysfunction as a predictor of sudden cardiac death in hypertrophic cardiomyopathy: a strain-based analysis

Background

In hypertrophic cardiomyopathy (HCM), left atrial (LA) dysfunction—particularly impaired reservoir function and increased stiffness—may reflect chronic diastolic burden and underlying atrial fibrosis. These abnormalities have been associated with atrial and ventricular arrhythmias, including malignant arrhythmias that contribute to sudden cardiac death (SCD).

Objective

To investigate the association between echocardiographic LA functional parameters, including strain and stiffness index, and the estimated risk of SCD in patients with HCM.

Methods

We conducted a cross-sectional, comparative, single-center study of 35 patients with HCM between January and May 2025 at Charles Nicolle Hospital, Tunis. Participants were stratified into two groups according to the HCM Risk-SCD score:

• Group 1: high 5-year risk (≥6%, n = 10)

• Group 2: intermediate or low risk (<6%, n = 25)

Standard transthoracic echocardiography and two-dimensional speckle-tracking imaging were performed to assess LA strain components—reservoir (LAS-R), conduit (LAS-CD), and contraction strain (LAS-CT)—as well as the LA stiffness index (LASI). These parameters were compared between groups.

Results

The mean age of the cohort was 56.4 ± 14.2 years. Left ventricular ejection fraction and wall thickness did not differ significantly between the two groups (p = 0.28 and p = 0.32). In contrast, Group 1 (high-risk) showed significantly reduced LA strain values (LAS-R, LAS-CD, LAS-CT; p = 0.017, p = 0.001, and p = 0.005, respectively) and a markedly elevated LA stiffness index (p = 0.0001). High-risk patients also demonstrated higher E and E/e′ ratios (p = 0.009 and p = 0.005), increased prevalence of mitral regurgitation (p = 0.005), and larger LA dimensions (p = 0.05).

Conclusion

In patients with HCM, impaired LA function—reflected by reduced LA strain and increased stiffness—is strongly associated with a higher estimated risk of sudden cardiac death. These findings support the potential role of LA functional parameters as complementary markers for SCD risk stratification and may enhance current risk prediction models in HCM.