MedWire News: Obesity is the most important risk factor for the development of left atrial enlargement (LAE) in the general population, results of a 10-year study shows.
Hypertension also appeared to play a role in LAE but the authors speculate that it may act through different pathophysiologic mechanisms.
“With regard to the increasing prevalence of obesity in industrialized countries, development of effective primary prevention strategies are essential to avoid premature cardiovascular remodelling,” say study author Heribert Schunkert (University of Lübeck, Germany) and colleagues in the Journal of the American College of Cardiology.
Obesity and arterial hypertension are known to cause a variety of structural and functional cardiac changes.
Cardiac adaptation to obesity generally involves left ventricular (LV) dilation and increased LV mass with a pattern of eccentric hypertrophy, while hypertension, by contrast, results most frequently in a concentric increase of LV mass.
Both impair ventricular filling and thus facilitate the development of diastolic dysfunction, ultimately leading to LAE.
Since little is actually known about the determinants of LA size in the general population, the researchers addressed this question in 1212 individuals (48% male) aged an average of 48.5 years, living in the Augsburg area. LA volume was determined by standardized echocardiography.
The crude prevalence of LAE at baseline was 9.6% for men and 10.0% for women. Both obesity and hypertension were independent predictors for LAE prevalence at baseline, with odds ratios (ORs) of 2.4 and 2.2, respectively (p < 0.001 for both)
After 10 years’ follow-up the crude incidence of LAE was 18.7% for men and 21.1% for women. Obesity was a significant independent predictor for incident LAE (OR=2.7, p< 0.001), but hypertension failed to reach significance (OR=1.1).
Schunkert and colleagues suggest that LA pressure load in hypertensive individuals results in an increase in LA size early after occurrence of the disease, levelling out thereafter.
Meanwhile, chronic LA volume load in obese individuals results in a continuous enlargement of the left atrium – as indicated by significant associations with both prevalent and incident LAE.
Discussing their findings the researchers emphasize the importance of early interventions, especially in young obese individuals, but stress: “It remains unclear to what extent weight maintenance or moderate weight loss has beneficial effects, resulting in regression of LAE.”
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