Reading the results from the echo and the angiogram, I see only minor abnormalities, that do not explain his feeling very weak, giddiness and/or vomiting.
30-40% stenosis does not limit the blood flow to a level that it becomes noticeable. Treatment normally becomes necessary when the stenosis is more than 80%.
Grade1 diastolic dysfunction and mild concentric LVH are both minor abnormalities and although the Prolomet is probably described for it, imo it can not give the symptoms you describe.
Why did your husband have the angiogram when he has no chest pain?