Cytokine storm syndrome

https://www.sciencedaily.com/releases/2020/05/200513081810.h...

This, as well as Disseminated Intravascular Coagulation(DIC).

https://en.wikipedia.org/wiki/Disseminated_intravascular_coa...

https://emcrit.org/ibcc/covid19/#disseminated_intravascular_...

Ive heard its heart attack.

Most likely this. Low blood oxygen stresses the cardiovascular system so there are greater odds that anything that can go wrong there will.