Assessment of left ventricular dyssynchrony by real-time three-dimensional echocardiography

A number of different imaging methods have been proposed as possible tools for assessing left ventricular (LV) mechanical dyssynchrony. The aim of this study was to evaluate the usefulness of real-time three-dimensional echocardiography (RT3DE) for studying LV mechanical dyssynchrony.

In total, 60 individuals underwent RT3DE, including 10 healthy volunteers, 23 patients with acute ST-segment elevation myocardial infarction and 27 patients with dilated cardiomyopathy. The LV volume was recorded throughout the full cardiac cycle using RT3DE, after which LV mechanical dyssynchrony was determined. The extent of LV mechanical dyssynchrony was characterized using the systolic dyssynchrony index (SDI), which was calculated from the variation in the time required to reach the minimum regional systolic volume in the 16 LV segments analyzed.

The SDI was significantly higher in patients with dilated cardiomyopathy, at 14.3%+/-7.5% compared with 1.5%+/-0.7% in healthy volunteers and 8.1%+/-7.1% in acute myocardial infarction patients (ANOVA, P< .001). Basal and mid ventricular segments showed the greatest delays. All patients with dilated cardiomyopathy received cardiac resynchronization therapy. In this patient subgroup, the SDI exhibited an immediate significant decrease (to 9.7%+/-6.8%; P< .05) and a progressive decrease during 6 months of follow-up (to 4.9%+/-3.1%; P< .05).

The new imaging technique of RT3DE can be used to assess LV mechanical dyssynchrony and is able to identify the LV segments with the greatest time delays.