Implications of Indeterminate and Determined Etiologies Leading to Small Left Atria

Small left atria (LA) is associated with an increased risk of mortality.

To determine whether the attributed risk of mortality is influenced by the underlying etiologies leading to decreased volumes.

We retrospectively evaluated patients with an available LA volume index (LAVI) as measured by echocardiography who came to our institution between 2011 and 2016. Individuals with small LA (LAVI < 16 ml/m2) were included and divided according to the etiology of the small LA (determined or indeterminate) and investigated according to the specific etiology.

The cohort consisted of 288 patients with a mean age of 56 ± 18 years. An etiology for small LA was determined in 84% (n=242). The 1-year mortality rate of the entire cohort was 20.5%. Patients with indeterminate etiology (n=46) demonstrated a lower mortality rate compared with determined etiologies (8.7% vs. 22.7%, P = 0.031). However, following propensity score adjustments for baseline characteristics, there was no significant difference between the groups (P = 0.149). The only specific etiology independently associated with 1-year mortality was the presence of space occupying lesions (odds ratio 3.26, 95% confidence interval 1.02-10.39, P = 0.045).

Small LA serve as a marker for negative outcomes, and even in cases of undetected etiology, the prognosis remains poor. The presence of small LA should alert the physician to a high risk of mortality, regardless of the underlying disease.