Mitral valve. Valve leaflate sec to?

My father is undergoing from open heart surgery before 8 years back.. And then his health is good... But now when we done 2d echo.. Report suggest that, LA/RA/RV Dilated, LV normal size, no hypertrophy, No LV RWMA, good LV/RV SYSTOLIC function (LVEF-55%),E/O prosthetic at Mitra position decreased movment of prosthetic valve leaflate sec to? pannaus formation. nnormaly, aortic valve thickened, other cardiac valve are normal, no vegetation/ no effusion. E/o clot in LA. DOPPLER AND COLOR DOPPLER P/M ACROSS prosthetic Mitral Valve 24/14 mm of he, MVA by PHT 0.74 cm2 Grade 2 AR, NO AS, NO e/o prosthetic valvular and paravalvular regurgitation Grade 1 TR, PASP by TR jet 55 mm of hg CONCLUSION Prosthetic valve in Mitral position E/o Prosthetic valve dysfunction sec to Pannus formation ,mild aortic regurgitation, moderate pulmonary hypertension, No LV RWMA, GOOD LV/RV systolic function . So doctor told us to do again open heart surgery.. SO MY QUESTION IS THERE ANY OTHER TREATMENT.