Association of computed tomography-derived left atrial size with major cardiovascular events in the general population: the Heinz Nixdorf Recall Study.

Background: Echocardiography based data suggests that left atrial (LA) size is associated with cardiovascular morbidity and mortality. Once non-contrast cardiac CT is performed for prevention purposes, information on the LA is readily available. We aimed to determine whether LA area from non-contrast cardiac CT is associated with incident major cardiovascular (CV) events, independent of CV risk factors and coronary artery calcium (CAC), based on a general population cohort.

Methods: Subjects aged 45-75 years without prevalent CV disease from the population-based Heinz Nixdorf Recall Study were enrolled between 2000 and 2003. LA area at the level of the mitral valve was quantified from non-contrast cardiac CT. Major CV events (coronary event, stroke, CV death) were assessed during follow-up. The association of LA with events was assessed using Cox regression analysis.

Results: Overall, 3958 subjects (59.2 ± 7.7 years, 53% female) were included. Mean LA area was 17.64 ± 4.22 cm(2) (range: 7.16-44.13 cm(2)). During 8.0 ± 1.5 years of follow-up, 221 major CV events occurred. In univariate analysis, increase of LA size by 1 standard deviation was associated with nearly 50% excess events (HR (95%CI): 1.48 (1.32-1.65)), which remained significant after adjustment for CV risk factors (HR (95%CI): 1.25 (1.09-1.43)) and when additionally adjusting for CAC (HR (95%CI): 1.22 (1.07-1.40)). Associations for LA size were similar for each endpoint and again independent of risk factors and CAC (coronary event: HR (95%CI): 1.21 (1.01-1.45); stroke: 1.31 (1.05-1.63); CV death: 1.33 (1.03-1.71)).

Conclusion: LA size is associated with incident major CV events independent of risk factors and CAC-score. Once cardiac CT imaging is performed, assessment of LA size may complement information of this imaging modality.