How serious it is, is a factor.
You can lessen the degree of it somewhat though regular vacuum pumping and some other PE exercises by making your penile arterial system more efficient. You can often work around it very effectively using one or another of the ED drugs. Cock rings are very helpful.
There is surgery for venous leakage with pretty good results in the hands of a highly experienced surgeon. Results are good but do not always last.
This is not a condition you can self-diagnose. Further, men with ED often assume they have venous leakage when they have something else. There is a very good test for it called a Doppler Color Sonogram which can pretty accurately pin-point areas of leakage if there are any. The problem is, what do you then do with the information?