How does one evaluate the severity of the mitral stenosis with auscultation?
The shorter the S2 to opening snap (S2-OS) interval, the more severe the mitral stenosis. Higher left atrial pressure in early diastole will snap the valve open faster than a lower pressure situation.
The higher the intensity and the longer the duration of the rumble in diastole does correlate with the severity of the stenosis. But these qualities are more dependent on flow i.e. cardiac output. A decreasing cardiac output in the presence of a great degree of mitral stenosis might actually make a murmur softer than expected.