Da T. Tran

Left ventricular longitudinal and radial synchrony and their determinants in healthy subjects

OBJECTIVE The reference values and impact of physiologic variables on echocardiographic quantification of left ventricular (LV) synchrony in a large series of healthy persons are unknown. This study prospectively investigated the impact of age, gender, and other physiologic parameters on LV longitudinal and radial synchrony. METHODS LV longitudinal systolic and diastolic synchrony using tissue Doppler imaging were measured as the standard deviation of times to 12 regional peak myocardial systolic Sm (SDTs) and early diastolic Em (SDTe) velocities in 122 healthy volunteers (age 19-68 years, 64 men). By using 2-dimensional speckle tracking, radial synchrony was measured as the standard deviation of times to 6 regional peak strain (SDTrepsilon) in the short-axis papillary muscle level. Longitudinal systolic synchrony was also measured as the standard deviation of times to 12 regional peak strain (SDTlepsilon). RESULTS The mean QRS duration and LV ejection fraction were 87 +/- 12 msec and 61% +/- 5.5%, respectively. The mean SDTs and SDTe were 37.1 +/- 17.4 msec and 17.3 +/- 6.7 msec, respectively. Gender and the mean Sm velocity from the 6 basal LV segments were independent predictors of SDTs, whereas the isovolumic relaxation time and mean Em velocity independently predicted SDTe. The mean SDTrepsilon was 19.2 +/- 14.6 msec. SDTrepsilon did not correlate with any clinical or echocardiographic parameters. The mean SDTlepsilon was 40.4 +/- 11.8 msec. Isovolumic relaxation time, pulmonary S/D ratio, and mean Sm independently predicted SDTlepsilon. There was no correlation between LV longitudinal and radial synchrony. Intraobserver and interobserver variability analyses showed the highest correlation for SDTs compared with SDTrepsilon and SDTlepsilon. CONCLUSION This study establishes normal reference ranges for LV systolic and diastolic synchrony measured with tissue Doppler velocity-based and 2-dimensional speckle tracking-based methods in a large group of healthy subjects of both genders across a wide age group. SDTs is gender specific and dependent on global LV systolic function, whereas SDTe is dependent on global LV diastolic function. Two-dimensional speckle-derived radial synchrony is independent of any clinical and echocardiographic variables but has higher intraobserver and interobserver variability compared with SDTs. LV longitudinal synchrony does not correlate with radial synchrony.

Comparison of Myocardial Tissue Velocities Measured by Two-Dimensional Speckle Tracking and Tissue Doppler Imaging

Myocardial velocities have prognostic implications, and transmitral E wave to mitral annular early diastolic tissue velocity ratio (E/Em) is utilized to estimate left ventricular (LV) end-diastolic pressure (EDP). There are no reference values for 2-dimensional (2D) speckle tracking myocardial velocities (S2D, E2D, A2D), and it is unknown if they are comparable with color tissue Doppler imaging (TDI). Predictors of E/E2D ratios are unknown and E/E2D has not been validated with LVEDP. The myocardial velocities of 142 subjects were measured by TDI and 2D speckle tracking. Mean E/Em and E/E2D were calculated as transmitral E wave to mean 6 basal early diastolic myocardial velocities using TDI and 2D speckle tracking respectively, and compared with LVEDP during catheterizations (n = 20). Mean E2D was lower but mean S2D and A2D were higher than TDI (all p <0.001). When TDI sample volume was tracked throughout the cardiac cycle, this directional difference was no longer apparent with S2D, E2D, and A2D higher than TDI (all p <0.05). Age, systolic blood pressure, LV ejection fraction, and mean S2D were independent correlates of E/E2D. Receiver-operator characteristic analysis showed E/E2D (p = 0.03), not E/Em, identified elevated LVEDP (> or =12 mm Hg). E/E2D of 11.6 had 83% sensitivity and 70% specificity to predict elevated LVEDP. In conclusion, TDI and 2D speckle tracking myocardial velocities are not comparable due to angle independency and ability for tissue tracking with the latter. LV systolic function, age, and afterload are independent correlates of E/E2D. Only E/E2D identifies elevated LVEDP, and an E/E2D of 11.6 has the optimal sensitivity and specificity.

Comparison of Left Ventricular Dyssynchrony by Two-Dimensional Speckle Tracking Versus Tissue Doppler Imaging in Patients With Non-ST-Elevation Myocardial Infarction and Preserved Left Ventricular Systolic Function

Assessment of left ventricular (LV) dyssynchrony after myocardial infarction has prognostic value. There were no reference ranges for 2-dimensional (2D) speckle tracking synchrony, and it was unclear whether color tissue Doppler imaging and 2D speckle tracking synchrony indexes were comparable. One hundred twenty-two healthy volunteers and 40 patients with non-ST-elevation myocardial infarction (NSTEMI) had LV systolic and diastolic synchrony, defined as the SD of time to peak systolic (2D-SDTs) and early diastolic (2D-SDTe) velocities in the 12 basal and mid segments using 2D speckle tracking, respectively. Mean 2D-SDTs and 2D-SDTe were 29.4 +/- 16.1 and 14.2 +/- 6.1 ms in healthy subjects, respectively. Gender and mean 2D systolic velocity independently predicted 2D-SDTs, and mean 2D early diastolic velocity independently predicted 2D-SDTe. Bland-Altman analysis showed suboptimal agreement between 2D speckle tracking and tissue Doppler imaging dyssynchrony indexes. 2D speckle tracking showed lower coefficients of variation for time to peak systolic and early diastolic velocities than tissue Doppler imaging. There were no significant differences in coefficients of variation for 2D speckle tracking systolic and diastolic synchrony for high versus low frame rates. Patients with NSTEMI had significantly lower ejection fraction, but higher LV mass and wall stress than healthy subjects. Only 2D-SDTs was significantly higher in patients with NSTEMI compared with healthy subjects (37.1 +/- 22.5 vs 29.4 +/- 16.1 ms; p = 0.02). In conclusion, 2D-SDTs was gender specific and influenced by global systolic function, and 2D-SDTe was influenced by global diastolic function. 2D speckle tracking and tissue Doppler imaging dyssynchrony indexes were not comparable. 2D speckle tracking may be a more sensitive discriminator of LV systolic dyssynchrony than tissue Doppler imaging.

Prognostic implications of left ventricular dyssynchrony early after non-ST elevation myocardial infarction without congestive heart failure

AIMS To determine independent predictors of left ventricular (LV) dyssynchrony after non-ST elevation myocardial infarction (NSTEMI) and prognostic value of combining dyssynchrony parameters for long-term LV dysfunction. METHODS AND RESULTS Left ventricular dyssynchrony assessments were performed in 100 NSTEMI patients followed-up for 1 year using a composite dyssynchrony score. Early LV dyssynchrony was independently predicted by the presence of significant proximal left circumflex artery (LCx) stenosis and global systolic dysfunction. Left ventricular end-diastolic volume index decreased with time and was independently determined by a lower number of diseased vessels and the absence of early dyssynchrony. Left ventricular end-systolic volume index decreased with time and was independently determined by the absence of early dyssynchrony, lower number of diseased vessels, and revascularization. Left ventricular ejection fraction increased with time and was independently determined by the absence of early dyssynchrony, lower number of diseased vessels, and revascularization. The composite dyssynchrony score was an independent determinant of a persistently dilated LV and low LVEF at follow-up. CONCLUSION After NSTEMI, proximal LCx stenosis and impaired LV function independently predicted LV dyssynchrony. The composite dyssynchrony score had prognostic value and identified patients with persistently dilated and impaired LV on follow-up.