The short answer
Yes. High LDL causes no symptoms while it builds plaque in your arteries, and the first sign can be a heart attack or stroke.
How much it matters depends on how high your LDL-C is, how many years it stays high, and your other risks: blood pressure, smoking, diabetes, kidney disease and family history.
The good news is that lowering LDL works, and the sooner it comes down, the more you protect your arteries.
Source: 2018 AHA/ACC cholesterol guideline; European Atherosclerosis Society consensus, Eur Heart J 2017.