C1721: Cardioverter-defibrillator, dual chamber (implantable)
C1721 is a HCPCS Level II code for cardioverter-defibrillator, dual chamber (implantable). It belongs to the Outpatient Prospective Payment System section. Whether Medicare pays it depends on the coverage rule below.
Medicare coverage: Special coverage instructions apply
There are published conditions attached to this code. Check the applicable coverage policy before billing it: the code being valid is not the same as the service being covered.
From the coverage field of the CMS Alpha-Numeric HCPCS File, release 2026Q4-Oct. This states Medicare’s position on the code, not on your particular claim.
Medically Unlikely Edits: units per day
The most units of C1721 Medicare will pay on one date of service. Bill more on a single line and it is denied. The limit is not the same in every setting, so the row that matters is the one matching the claim you are building.
- practitioner
- 1 unit MAI 3: Date of Service Edit: Clinical · Nature of Equipment
- outpatient
- 1 unit MAI 3: Date of Service Edit: Clinical · Nature of Equipment
The adjudication indicator decides whether exceeding the limit is worth appealing at all: MAI 1 is a line edit you can support with documentation, MAI 3 is a date-of-service edit that is also appealable, and MAI 2 is absolute, no documentation overrides it. CMS MUE 2026Q4.
The CMS record for C1721
- Long descriptor
- Cardioverter-defibrillator, dual chamber (implantable)
- Short descriptor
- Aicd, dual chamber
- Added
- April 1, 2001
- BETOS
- D1A
- Pricing indicator
- 53: Other
The official wording. This is what the code means.
CMS's 28-character form, which is what shows up on a remittance advice.
When CMS introduced the code.
Berenson-Eggers Type of Service: CMS's own analytic grouping.
Statute.
Codes adjacent to C1721
HCPCS has no hierarchy: related items simply sit next to each other in the numbering. If C1721 is not quite right, the correct code is very often within a few positions of it.
- C1608Prosthesis, total, dual mobility, first carpometacarpal joint (implantable)
- C1609Vertebral device, motion-preserving, with screw fixation
- C1713Anchor/screw for opposing bone-to-bone or soft tissue-to-bone (implantable)
- C1714Catheter, transluminal atherectomy, directional
- C1715Brachytherapy needle
- C1716Brachytherapy source, non-stranded, gold-198, per source
- C1717Brachytherapy source, non-stranded, high dose rate iridium-192, per source
- C1719Brachytherapy source, non-stranded, non-high dose rate iridium-192, per source
- C1722Cardioverter-defibrillator, single chamber (implantable)
- C1724Catheter, transluminal atherectomy, rotational
- C1725Catheter, transluminal angioplasty, non-laser (may include guidance, infusion/perfusion capability)
- C1726Catheter, balloon dilatation, non-vascular
- C1727Catheter, balloon tissue dissector, non-vascular (insertable)
- C1728Catheter, brachytherapy seed administration
- C1729Catheter, drainage
- C1730Catheter, electrophysiology, diagnostic, other than 3d mapping (19 or fewer electrodes)