My sister has a leaking heart valve and she is 27 could she have go get a pacemaker when she gets older?

Unlikely: Valvular heart disease is a "plumbing" problem while arrhythmias and pacemakers are more electrical issues. Of course, there is some overlap, but generally speaking, those are somewhat unrelated issues. Leaking heart valves, if significant, may eventually require medication or even intervention or surgery. Pacemakers are not really part of the therapy unless a rhythm problem eventually develops.