The aim of this study was to evaluate the effects of acute right ventricular (RV) pressure overload (RVPO) on RV systolic function and its regional uniformity using speckle-tracking strain analysis in patients with acute pulmonary thromboembolism (APTE). Twenty-three patients with APTE (mean age, 59 +/- 16 years) and 23 age-matched and gender-matched normal subjects (the control group) were examined using echocardiography. Global and segmental longitudinal RV peak systolic strain (PSS) was analyzed using speckle-tracking strain echocardiography. The heterogeneity of RV regional function was assessed by calculating the standard deviation from 6-segmental PSS divided by the absolute value of global PSS. The standard deviation of the heart rate-corrected intervals from QRS onset to PSS for the 6 segments was used to quantify RV dyssynchrony. Patients with APTE had reduced regional PSS, resulting in reduced global PSS and augmented regional heterogeneity, and had delayed myocardial contraction in the basal and mid RV lateral walls, resulting in large dyssynchrony (global PSS, -14 +/- vs -25 +/- 3%; heterogeneity, 0.54 +/- 0.26 vs 0.24 +/- 0.09; dyssynchrony, 91 +/- 38 vs 25 +/- 10 ms; P < .05 vs controls for all comparisons). After the amelioration of acute RVPO by primary treatment, both RV heterogeneity and dyssynchrony returned to normal values. Speckle-tracking strain echocardiography can effectively quantify reversible RV regional nonuniformity caused by acute RVPO and can characterize the pattern of RV regional impairment in patients with APTE.