Left Atrial Enlargement Is Related to Diastolic Dysfunction in Obese Subjects

PURPOSE: Obesity is linked to diastolic dysfunction and left atrial enlargement (LAE). The mechanisms responsible for LAE in obesity are unknown. We hypothesized that diastolic dysfunction, which is common in obesity, is the mechanism through which LAE occurs. METHODS: 27 middle-aged, obese patients (8M: 19F, 49±7years) with an average body mass index (BMI) of 38 ±5 kg/m2 were compared to age and sex matched non-obese healthy controls. Diastolic function (IVRT; isovolumic relaxation time, Vp: propagation velocity) was assessed using echocardiography. Left atrium (LA) size was measured using 3D echocardiogram, and normalized to height to account for the effects of body size. RESULTS: Obese individuals had a significantly enlarged atrial volume when compared to healthy individuals (35.9 ± 8 vs. 19.4 ± 10.5 mL/m; p<0.01). Obese patients had a significantly shorter IVRT when compared to non-obese patients (68 ± 11 vs 100 ± 16 msec; p<0.01). Obese patients also had a significantly faster Vp when compared to non-obese patients (75 ± 19 vs 56 ± 13 cm/sec; p<0.01). In obese subjects, there was a significant negative-relationship between LA volume index and IVRT (R2=0.27; p<0.05) as well as a significant positive-relationship between LA volume index and Vp (R2=0.18; p<0.05). CONCLUSIONS: Obese patients have larger LA and markers of elevated LA filling pressures (IVRT and Vp) compared to age matched controls. LAE in obesity may be a driven by sub-clinical alterations in diastolic function and left atrial filling pressures.