What are reasonable next steps in the work-up of suspected ATTR amyloidosis if the PYP scan is equivocal, in light of the potential risks of endomyocardial biopsy?

Before addressing the next move after an equivocal PYP scan, some comments on PYP scan reporting are in order. Unfortunately, despite the relative simplicity of obtaining a high quality PYP scam, around 10 -20% of the ones that we see done at outside institutions (including teaching institutions) ar...