Abstract 8935: Differentiation of Left Atrial Volume by Time Measured by Speckle Tracking Echocardiography as a Novel Index of Left Atrial Global and Phasic Function
Background: Left atrial (LA) strain rate (SR) is proposed to assess LA relaxation, conduit function and contraction. Differentiation of strain by time (SR) is one dimensional parameter, but differentiation of LA volume by time (dV/dt) is three dimensional parameter. Thus, we hypothesized that LA dV/dt is more useful index of LA global and phasic function.
Methods: We examined 138 subjects; normal (n=54, age 69±11 yrs, 30 men), hypertensive pts (HTN) with normal systolic function (n=84, age 71±9 yrs, 48 men). LA peak dV/dt and SR at systole, early diastole and atrial contraction were measured by speckle tracking which can automatically provide dV/dt from time-LA volume curve (Figure). LA peak dV/dt and SR in HTN were compared to normal. Time from onset of R wave on ECG to peak dV/dt at each phase was compared to that to peak SR.
Results: Inter and intraobserver correlation coefficient for dV/dt at each phase was 0.97-0.99. There was a good relation between dV/dt and SR (r=0.94, p<0.01). Time to peak dV/dt was comparable to time to peak SR at each phase (208±62 vs. 189±56, 523±50 vs. 527±51, 921±161 vs. 920±162msec, respectively, p<0.01). Peak positive dV/dt and SR at systole in HTN were reduced compared to normal (178±35 vs. 204±47 ml/s, 1.1±0.3 vs. 1.3±0.4 s-1, respectively, p<0.05). Peak negative dV/dt and SR at early diastole in HTN were lower (-174±62 vs. -216±92ml/s, -0.9±0.3 vs. -1.4±0.6 s-1, respectively, p<0.05), associated with elevated E/e’ (9.0±1.9 vs. 7.2±1.9, p<0.01). Despite no difference in peak SR at atrial contraction between 2 groups, peak negative dV/dt in HTN was higher than normal (-222±67 vs. -147±74 ml/s, p<0.01).
Conclusions: LA relaxation assessed by dV/dt and SR was reduced in HTN and conduit function was also reduced in HTN by impaired diastolic function. LA active contraction assessed by dV/dt was increased in HTN to compensate reduced conduit function. Measurement of LA dV/dt may be more promising method to assess LA function with highly acceptable variability.
- © 2011 by American Heart Association, Inc.