If you have syncope, it is also definitely prudent to have that engraved on the
bracelet. First responders DO know what syncope is!! (
No need to bother with "neurocardiogenic syncope" or "vasovagal syncope," etc., just "syncope" will suffice.)
Whether you want to put Aspergers on there or not is up to you, but outside of the Autism community, the ASD abbreviation is not well known, so I wouldn't use that initialism for the engraving.