Cardiomyoapthy and Nonsustained VT

My husband is 48 year old. He was diagnosed with PVCs about 9 years ago. In 2006 monomorphic PVC were ablated from RV and they decreased from 20000 to about 110 in 24 hours. Two MRAs (2 years apart) were normal.
He has never had any syptoms (symptoms) but because echocardiogram showed midly dilated left ventricle and EF dropped to 40% before ablation, he was treated with coreg and lisinopril. He had normal stress test.His EF improved to 53% 1 year after ablation (November 2008).
How he had another holter showing 500+ PVCs and 8 runs of nonsustained VT (up to 8 beats).

I am very concerned about this finding. He is to have another MRA and echocardiogram done.

What is the prognosis in his case?
How many year ?
Should we expect that he will have increased number of VT in the next years ?
Wold you suggest any other tests or treatments

[Cleveland Clinic]

The prognosis is good.  I am not that concerned about the 500+ PVC's nor the episodes of NSVT.  His Ejection fraction is normal, so he should stay on the beta blocker to prevent these episodes from becoming more frequent or clinically significant.
It's hard to say whether these episodes will become more frequent.  As long as his heart function is normal he should do well.