Thanks for writing to us.
As per the current guidelines a person who has established Rheumatic heart disease
(as in case of your wife) the person should take penidura for ~10 years after last attack of rheumatic fever
or at least well into middle adulthood whichever is later And those who have undergone valve replacement
should take it life long. now there are 2 issues, no clear cut age is mentioned for "middle adulthood" (although a number of clinicians take it as 40) and second BMV is an intervention but not a valve replacement. the basic intent is that patient should not be having a risk of rheumatic fever again which depends upon a number of other factors.
overall i would say, yes she may be able to stop this injection but the person who can decide upon this is her treating cardiologist, who will consider all the factors before taking this decision.