Show your work (intervening steps) please?
...I wasn’t aware the innate immune system would attack the body’s own tissues.
Unless you are suggesting spike protein is being presented from the cell walls of cardiac cells?
And presumably, the swelling isn’t inside the lining of the chambers themselves, but inside the muscle, where the blood flow through the capillaries supplying the heart is less, giving time for the lipid complex to be taken into cells.
(How many ACE2 receptors do cardiac cells have? Alternative mechanism is free spike reacting with cardiac cells setting off an inflammatory cascade.) /hand-waving>
Auto-immune diseases have been recognized for a long time.
https://www.niehs.nih.gov/health/topics/conditions/autoimmune/index.cfm
Here is a study indicating the combination of RNA and spike protein (more speculative) can be involved in heart fibrosis.
https://pubmed.ncbi.nlm.nih.gov/24259498/