Usually, when the systolic level is high it is due to a higher than normal resistance the heart pumps against. The higher resistance can be caused by inflexible and some narrowing of the vessels.
If the high resistance isn't successfully treated, the heart's left ventricle can/will enlarge due to the increased workload. Lisinopril is medication that dilates blood vessels, and that will/should reduce the heart's workload. Additionally, if your lipid level is within normal limits that can reduce the risk for vessel blockage with plaque.
Hope this helps, and if you have any additional questions you are welcome to followup. Take care.