Are measures of left ventricular systolic performance during low dose dobutamine stress echocardiograms repeatable over time?

To establish the test-retest reliability and the normal dose-response relationship of echocardiographic measures of Left Ventricular (LV) contractile function to low dose dobutamine stress in healthy individuals. Thirty healthy volunteers (23 males, 7 females) with an average age of 38 ± 13 years underwent dobutamine stress echocardiography (DSE) (at successive doses of 0, 5, 10, and 20 mcg/kg/min) on two occasions, separated by 14 days. Ejection fraction (EF) was determined from 2D echocardiographic measures of left ventricular (LV) end diastolic and end systolic volumes. Longitudinal strain (S) and strain rate (SR) were measured using 2D speckle tracking analysis from three consecutive cardiac cycles. The Intraclass Correlation Coefficient (ICC) and the Coefficient of Variation (CV) were calculated to assess reliability and variability of the study population's EF, S, and SR responses to increasing doses of dobutamine. Left ventricular S and EF gradually increased with low doses of dobutamine but reached a plateau between 10 and 20 mcg/kg/min. Strain rate, however, gradually increases with each increasing dose of dobutamine. These responses were replicated on Day 2 with a high degree of reliability as determined from the ICC and low variability as determined from the CV, which fell within acceptable limits (<10 %). Left ventricular EF, S and SR can be measured during DSE with a high degree of test-retest reliability, and may be of clinical value when serial follow up of DSE measures of LV performance is indicated over time.