Left atrial compensatory function in subjects with early stage primary hypertension assessed by using left atrial volumetric emptying fraction acquired by transthoracic echocardiography

PurposeTo evaluate left atrial (LA) function in subjects with early stage primary hypertension (HT) and without enlargement of LA, we used transthoracic echocardiogram and measured LA volumetric emptying fraction and compared the results with those in healthy volunteers.Materials and methods42 subjects with early stage primary HT (21 males, aged 61 ± 12 years), within 1 year of HT diagnosis and starting initial treatment, were enrolled in the study. An additional inclusion criterion was normal sinus rhythm electrocardiogram without enlargement of LA. As the control group, 31 healthy volunteers with normal sinus rhythm electrocardiogram (13 male, aged 57 ± 11 years) were enrolled. Maximum and minimum volume of LA (LAV max and min, respectively) were selected manually and visually in B mode images acquired from a four-chamber view from apex of left ventricle (LV) using a modified Simpson method, and the LA emptying fraction (LAEF) was calculated by the following formula: LAV min / LAV max × 100 (%).ResultsThere were no significant differences in age, male:female ratio, end-diastolic and end-systolic LV diameter, LA maximum volume, LV ejection fraction and E/A in mitral annulus between the two groups. However, we found that end-diastolic inter-ventricular septum thickness and end-diastolic LV posterior wall thickness were significantly larger in the HT group in comparison with the control group (P < 0.01), but the HT group did not fit the classical criteria of LV myocardial hypertrophy. The systolic and diastolic blood pressure, the end-diastolic and end-systolic volume of LV, the total weight of LV myocardium and the LAEF were significantly higher in the HT group than in the control group (P < 0.05).ConclusionsIn subjects with early stage primary HT with normal sinus rhythm, in spite of a normal LAV, the LAEF may increase. This increase of LAEF may be regarded as one of the compensatory reactions against preload to the left side of the heart and precedes the occurrence of LA enlargement.