A device for assessment and therapy of temporal ventricular desynchronization in a patient, of the type comprising: - an hemodynamic sensor (32, 36), adapted to deliver a signal representative of a flow of blood in the left cavities of the myocardium; - at least one movement sensor (40, 44), adapted to deliver a signal representative of a displacement of the walls of the left ventricle of the myocardium; - first analysis means, adapted to determine an instant of closure of the aortic valve based on the signal of the hemodynamic sensor; - second analysis means, adapted to detect and assess a peak of contraction of the left ventricle based on the signal(s) of the movement sensor(s); and - means for bi-, tri- or multi-ventricular stimulation, adapted to deliver stimulation pulses intended to be applied to electrodes respectively implanted in at least one right ventricular stimulation site and at least one left ventricular stimulation site, according to a current stimulation configuration with application of at least one modifiable interventricular delay VVD and/or atrioventricular delay AVD, the device being characterized in that: - the second analysis means are adapted to determine an instant (P L) of said peak of contraction of the left ventricle; and in that it further comprises: - third analysis means, adapted to measure a time difference (ΔT) between the instant (P L) of the peak of contraction of the left ventricle and the instant of closure of the aortic valve; and - means adapted, if the third analysis means determine that the instant (P L) of the peak of contraction of the left ventricle is posterior to the instant of closure of the aortic valve, to modify the VVD and/or AVD of the current stimulation configuration in a direction reducing and cancelling the delay (ΔT) of the peak of contraction of the left ventricle after the closure of the aortic valve. - an hemodynamic sensor (32, 36), adapted to deliver a signal representative of a flow of blood in the left cavities of the myocardium; - at least one movement sensor (40, 44), adapted to deliver a signal representative of a displacement of the walls of the left ventricle of the myocardium; - first analysis means, adapted to determine an instant of closure of the aortic valve based on the signal of the hemodynamic sensor; - second analysis means, adapted to detect and assess a peak of contraction of the left ventricle based on the signal(s) of the movement sensor(s); and - means for bi-, tri- or multi-ventricular stimulation, adapted to deliver stimulation pulses intended to be applied to electrodes respectively implanted in at least one right ventricular stimulation site and at least one left ventricular stimulation site, according to a current stimulation configuration with application of at least one modifiable interventricular delay VVD and/or atrioventricular delay AVD, - the second analysis means are adapted to determine an instant (P L) of said peak of contraction of the left ventricle; - third analysis means, adapted to measure a time difference (ΔT) between the instant (P L) of the peak of contraction of the left ventricle and the instant of closure of the aortic valve; and - means adapted, if the third analysis means determine that the instant (P L) of the peak of contraction of the left ventricle is posterior to the instant of closure of the aortic valve, to modify the VVD and/or AVD of the current stimulation configuration in a direction reducing and cancelling the delay (ΔT) of the peak of contraction of the left ventricle after the closure of the aortic valve.