Characterization of left atrial function in hypertensive patients. Cardiovascular magnetic resonance study

Abstract

Purpose: Left atrial (LA) function includes reservoir, conduit and booster pump functions. In stiff ventricles these change in order to improve the filling. The aim of the study was to assess these changes in hypertensive patients (HT) with cardiovascular magnetic resonance (CMR). Methods: HT subjects referred for a clinical CMR and who did not have signs of myocardial necrosis, no cardiomyopathy except HT, no significant valve disease and no signs of secondary HT were included and compared to matched normotensives (NT). Cine sequences were acquired in a short axis stack of the atria and ventricles. LA volumes (maximum= LAmax, pre-atrial contraction= LAa, minimum= LAmin) were quantified. Several parameters were calculated for reservoir function (expansion index= (LAmax-LAmin)*100/LAmin; total emptying fraction= (LAmax-LAmin)*100/LAmax), conduit function (passive emptying percentage = (LAmax-LAa)*100/(LAmax-LAmin); passive emptying fraction= (LAmax-LAa)*100/LAmax) and pump function (active emptying percentage = (LAa-LAmin)*100/(LAmax-LAmin); active emptying fraction= (LAa-LAmin)*100/LAa). Differences regarding these parameters were tested with ANOVA (factors: group, age, gender, BSA). Correlations with age and LV mass were explored. Results: 35 hypertensives (22 males, 35-80yrs) were included. They showed a significant decrease in parameters of reservoir and conduit functions, while the active emptying percentage was significantly increased. Results are shown on the table. Age correlated with LA volumes (LAmax, r= 0.48; LAa, r= 0.50; LAmin, r= 0.52), but not with LA function. LV mass was inversely correlated with parameters of reservoir function (expansion index, r= -0.597; total emptying fraction, r= -0.532) and relative wall mass was found to be inversely correlated with active emptying fraction (r= -0.464). Conclusions: In HT subjects a decrease in passive atrial function and an increased in pump function occur. These changes do not correlate with age but with LV mass (reservoir function) and relative wall mass (pump function), and might have prognostic implications.