Assessment of left ventricular untwisting by speckle-tracking echocardiography in patients with aortic regurgitation

Background: Left ventricular (LV) twist, as a result of counter-rotation of the apex and base during systole, and its subsequent untwisting during diastole represent important components of LV contractility and diastolic suction. Data regarding LV untwisting in AR patients are lacking. Purpose: To assess LV untwisting and its determinants in patients with significant chronic AR. Methods: We prospectively studied 35 patients withmoderate and severe chronic AR and 20 normal subjects. Exclusion criteria for AR patients were LV ejection fraction (LVEF) ≤50%, significant coronary artery disease, any LV wall motion abnormality, more than mild associated valvular heart disease, non-sinus rhythm. Basal and apical LV rotation and LV torsion were quantified from two-dimensional greyscale LV parasternal short-axis images by speckle tracking echocardiography (STE). LV untwisting was assessed by measuring peak untwisting velocity as the net difference in peak diastolic apical and basal rotation rates on the torsional velocity curve. Time to peak untwisting velocity (TTPUV) was normalized to diastolic duration. Analysis of left atrium (LA) strain and strain-rate parameters was performed on the same 4-chamber view in which LA volume was measured. Results: Age and gender of patients were similar in both groups. There was no difference in mean LVEF between groups (60±4% in AR group vs 62±3% in control group, p=0.15). Peak LV untwisting velocity was significantly reduced in the AR group compared with the control group (-117.7±35.0°/s vs -143.1±47.6°, p=0.028). Also, peak apical diastolic rotation rate was lower in the AR group (- 80.8±41.0°/s vs -105.0±32.7°/s p=0.028). TTPUV was similar in both groups (p=0.189). In AR patients, peak LV untwisting velocity correlated with peak apical diastolic rotation rate (r=0.75, p<0.001) but not with peak basal diastolic rotation rate (r=0.02, p=0.934). At univariate analysis, peak LV untwisting velocity correlated significantly with age (r=0.41, p=0.014), end-systolic LV volume (r=0.35, p=0.041), LV mass index (r=0.42, p=0.013), LA volume index (r=0.45, p=0.008), and peak early-diastolic LA strain rate (ESr) (r=0.51, p=0.004). At multivariable analysis LV mass index emerged as an independent determinant of peak LV untwisting velocity (p=0.044). Conclusions: LV untwisting is reduced in patients with significant AR and normal LVEF, and this is due to significantly decreased apical diastolic rotation rate. LV mass emerged as an independent determinant of LV untwisting velocity in these patients, suggesting that LV hypertrophy impacts on LV torsional dynamics in this setting.