Factors contributing to left atrial enlargement in adults with normal left ventricular systolic function.

BACKGROUND: Causes of left atrial (LA) enlargement and its gender difference in patients with normal left ventricular (LV) systolic function have not been clarified. We investigated the factors contributing to LA enlargement in patients with normal LV systolic function, addressing its gender difference.

METHODS: We enrolled 380 patients (175 males and 205 females; mean age: 63 + or - 15 years) with LV ejection fraction > or = 50% who underwent Doppler echocardiography and blood tests at the same time as echocardiography. Patients with arrhythmias, significant valvular heart disease, and LV asynergy were excluded. The LA volume was measured by Simpson's method from apical 2- and 4-chamber views, and LA volume index (LAVI) was calculated as LA volume/body surface area. All patients, male and female were assigned to a group with a low or a high LAVI based on the median LAVI value, respectively.

RESULTS: Age, female gender, hypertension, diabetes, hemoglobin concentration, LV mass index, Doppler parameters of LA contraction, and the ratio of mitral early diastolic velocity to early diastolic velocity of the mitral annulus (E/E') were significantly associated with a high LAVI in all patients. Multivariate analysis showed that LV mass index [odds ratio (OR) 1.05, 95% confidence interval (CI) 1.03-1.06, P<0.0001], hemoglobin concentration (OR 0.76, 95% CI 0.64-0.90, P<0.01), and female gender (OR 1.92, 95% CI 1.12-3.30, P<0.05) independently contributed to a high LAVI in all patients. In addition, LV mass index and hemoglobin concentration independently contributed to a high LAVI in both genders despite the absence of overt LV hypertrophy or anemia.

CONCLUSION: Increased LV wall thickness and decreased hemoglobin concentration might contribute to LA enlargement in patients with normal LV systolic function irrespective of gender.