To my knowledge, there is no "requirement" that either be sent by the specialist back to the PCP for a 99214. From a professional courtesy standpoint, either a copy of the office notes or or a letter which details the findings would be sufficient. I don't think it's really necessary to send both since the information in the two would be somewhat redundant.
Tom Cheezum, O.D., CPC
PS - when there were "consult" codes that could be used by the specialist, they did "require" that a report be sent back to the referring provider by the consulting physician in order for the consultant to bill for a consulting code. Those consulting codes aren't payable by Medicare or many other carriers any more.