Levosimendan reduces symptoms and improves hemodynamics in patients with acutely decompensated chronic heart failure (ADCHF). The aim of this study was to investigate (1) the association of changes induced by low-dose dobutamine stress echocardiography in 2-dimensional strain parameters with the corresponding changes in the left ventricular (LV) ejection fraction (EF) and LV outflow tract velocity time integral (VTI) in patients with ADCHF and (2) whether LV contractile reserve assessed by conventional and speckle-tracking echocardiography is associated with clinical and neurohumoral improvement after levosimendan treatment. Twenty-eight consecutive patients with ADCHF (mean age 65 +/- 10 years, mean New York Heart Association class 3.6 +/- 0.3, mean EF 22 +/- 6%) were studied using dobutamine stress echocardiography before 24-hour infusion of levosimendan. The LV EF, VTI, and mean longitudinal, circumferential, and radial strain and strain rate using speckle-tracking imaging were measured. Twenty-one patients (75%) had evidence of contractile reserve (LV EF increase >10% and VTI increase >20% after peak dobutamine dose). Patients with versus without contractile reserve demonstrated greater improvements in New York Heart Association class (mean change -1.0 +/- 0.5 vs -0.5 +/- 0.3, p = 0.01) and reductions in B-type natriuretic peptide levels (-34 +/- 30% vs +4 +/- 31%, p <0.01) 48 hours after treatment. On multivariate analysis, mean longitudinal systolic strain rate reserve (peak longitudinal strain rate minus longitudinal strain rate at rest) was the best predictor of improvement in New York Heart Association class (p = 0.039) and B-type natriuretic peptide level (p = 0.042) after levosimendan among the reserve of LV fractional shortening, the EF, VTI, and longitudinal, circumferential, and radial strain and strain rate. In conclusion, dobutamine-induced changes in longitudinal systolic strain rate are associated with clinical and neurohumoral improvement after levosimendan treatment in patients with ADCHF.