This is correct, but to the best of my knowledge the tissue samples required cannot be extracted from a living patient, requiring an autopsy. There may be exceptions based on risk to the patient for certain organs, but all the reports I've heard have been post mortem. To your point though, the autopsies to perform this type of test are not being conducted at the scale required to determine one way or the other as to what is causing the damage. This needs to change. There is obviously a clear signal surrounding the spike protein.

The test is called immunohistochemical staining.