From CMS:

IMPLEMENTATION DATE July 7, 2014: When a permanent pacemaker is implanted, there must be an attestation that there is documentation on file that the patient has non-reversible symptomatic bradycardia (symptoms of bradycardia are symptoms that can be directly attributable to a heart rate less than 60 beats per minute (for example: syncope, seizures, congestive heart failure, dizziness, or confusion)), as this is the only diagnosis that meets the NCD coverage requirements. This attestation will be made by appending modifier -KX, Requirements specified in the medical policy have been met, to CPT code 33206, 33207, or 33208. Specific diagnosis and inpatient procedure code requirements will also be implemented on this date.

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