It’s not the spike proteins. It’s the body’s immune system. If the LNPs deposit mRNA into the cells that line the Aorta, then those cells start producing spike (which is a problem, sure). The real problem with that is that your body’s immune system now wants to destroy those cells and anything around them that looks foreign (spike) so they lay waste to the lining of your Aorta, which weakens it and scars it up.

Now get another shot, more LNPs infest more Aortic cells in the damaged area. Immune system digs a deeper hole into the Aortic lining. Do that enough and you get a rupture (aneurysm) and bleed out in a minute or two.