In this paper the investigations of the dependence of the space-time projection structure and probability function form of speckle-interferometer output signal on heart disease seriousness have been carried out. The noval technique of heart disease diagnostic is suggested. The results of experimental investigations of pulse waves, using the differential speckle- interferometer are present. The traditional speckle-interferometer Michelson type and differential speckle-interferometer for cardiovibration measurements are compared. The difficulties, appearing by using suggested diagnostic method, are analyzed and ways to eliminate it are found.