A February 2020 study by Michigan State University looked at the fat around the arteries - perivascular adipose tissue (PVAT). It was thought that the main purpose of artery fat was just to store lipids.
The researchers said, "For years, we ignored this layer - in the lab it was thrown out; in the clinic it wasn't imaged. But now we're discovering it may be integral to our blood vessels." They found that it, “reduced the tension that blood vessels experience when stretched … And that's a good thing, because the vessel then expends less energy. It's not under as much stress."
"Our finding redefines what the functional blood vessels are and is part of what can be dysfunctional in diseases that afflict us, including hypertension. We need to pay attention to this layer of a blood vessel because it does far more than we originally thought."