Key facts for DRG 001
- FY2027 relative weight
- 28.0830
- Higher than 100% of all MS-DRGs
- Change vs FY2026
- +0.2%
- FY2026 weight 28.0240
- Geometric mean LOS
- 24.5 days
- Arithmetic mean 35.5 days
- MDC
- PRE
- Pre-MDC (transplants, tracheostomy, ECMO)
- Severity level
- with MCC (major complication or comorbidity)
- Transfer policy
- Not a transfer DRG
TL;DR
MS-DRG 001 is a surgical group in MDC PRE (Pre-MDC (transplants, tracheostomy, ECMO)) at the highest-severity level of its family. CMS assigns it a FY2027 relative weight of 28.0830 with a geometric mean length of stay of 24.5 days and an arithmetic mean of 35.5. Its weight moved up 0.2% from FY2026 (28.0240). That weight is higher than 100% of all surgical and medical MS-DRGs. Its CC/MCC family (DRG 002) spans weights 11.0040 to 28.0830. The v44 Definitions Manual assigns it through 4 operating room procedures codes and 56 implant of heart assist system codes.
What changed from FY2026 to FY2027
CMS recalibrates every MS-DRG weight annually from the prior year's MedPAR claims. For DRG 001 the FY2027 relative weight is 28.0830 against 28.0240 in FY2026, a rise of 0.21%.
| Metric | FY2026 | FY2027 | Change |
|---|---|---|---|
| Relative weight | 28.0240 | 28.0830 | +0.0590 |
| Geometric mean LOS (days) | 25.8 | 24.5 | -1.3 |
| Arithmetic mean LOS (days) | 36.2 | 35.5 | -0.7 |
CC and MCC family
DRG 001 shares its base definition with 1 other MS-DRG split by severity. The family's weights span 11.0040 to 28.0830, a 2.55× spread, which is the payment effect of documenting qualifying complications and comorbidities.
| DRG | Title | FY2027 weight | GMLOS |
|---|---|---|---|
| 001 | Heart Transplant or Implant of Heart Assist System with MCC | 28.0830 | 24.5 |
| 002 | Heart Transplant or Implant of Heart Assist System without MCC | 11.0040 | 9.4 |
Grouper logic (v44 Definitions Manual)
Operating Room Procedures: 4 ICD-10 codes drive assignment to this group.
| ICD-10 code | Description |
|---|---|
| 02YA0Z0 | Transplantation of Heart, Allogeneic, Open Approach |
| 02YA0Z1 | Transplantation of Heart, Syngeneic, Open Approach |
| 02YA0Z2 | Transplantation of Heart, Zooplastic, Open Approach |
| 02RK0JZ | Replacement of Right Ventricle with Synthetic Substitute, Open Approach |
Implant Of Heart Assist System: 56 ICD-10 codes drive assignment to this group; the first 12 are shown.
| ICD-10 code | Description |
|---|---|
| 02HA0QZ | Insertion of Implantable Heart Assist System into Heart, Open Approach |
| 02HA0RZ | Insertion of Short-term External Heart Assist System into Heart, Open Approach |
| 02HA3QZ | Insertion of Implantable Heart Assist System into Heart, Percutaneous Approach |
| 02HA4QZ | Insertion of Implantable Heart Assist System into Heart, Percutaneous Endoscopic Approach |
| 02RA0LZ | Replacement of Heart with Biologic and Synthetic Substitute, Autoregulated Electrohydraulic, Open Approach |
| 02RA0MZ | Replacement of Heart with Synthetic Substitute, Pneumatic, Open Approach |
| 02HA0RS | Insertion of Biventricular Short-term External Heart Assist System into Heart, Open Approach |
| 02HA0RS | Insertion of Biventricular Short-term External Heart Assist System into Heart, Open Approach |
| 02HA0RS | Insertion of Biventricular Short-term External Heart Assist System into Heart, Open Approach |
| 02HA0RZ | Insertion of Short-term External Heart Assist System into Heart, Open Approach |
| 02HA0RZ | Insertion of Short-term External Heart Assist System into Heart, Open Approach |
| 02HA0RZ | Insertion of Short-term External Heart Assist System into Heart, Open Approach |
Documentation and denial exposure
As a surgical DRG, assignment depends on a qualifying operating-room procedure being coded from the operative report; a missing or non-OR procedure code drops the stay into a medical DRG in MDC PRE with a lower weight. Because this family splits by severity, auditors target CC and MCC capture: each secondary diagnosis must be documented as present, monitored, evaluated or treated during the stay to survive a DRG-validation review. Typical inpatient denial codes for this group: CARC 16 (claim lacks information needed to group the stay), CARC 50 (the admission or procedure is judged not medically necessary), CARC 97 (a service is bundled into the DRG payment).
How QuickIntell uses DRG 001 data
QuickCode groups inpatient encounters against the current v44 logic, flags CC and MCC candidates that lack supporting documentation, and shows the weight difference across the family before the claim drops. QuickScribe captures the attending's language that supports severity, and QuickRCM works DRG-validation denials with the grouper evidence attached.
Frequently asked questions — DRG 001
What is MS-DRG 001?
MS-DRG 001 is "Heart Transplant or Implant of Heart Assist System with MCC", a surgical Medicare Severity Diagnosis-Related Group in MDC PRE, Pre-MDC (transplants, tracheostomy, ECMO). Medicare pays inpatient stays grouped here at the hospital's base rate multiplied by the DRG relative weight.
What is the FY2027 relative weight for DRG 001?
The FY2027 relative weight is 28.0830 (IPPS final rule Table 5, effective October 1, 2026). In FY2026 it was 28.0240, a change of +0.2%.
What is the average length of stay for DRG 001?
CMS reports a geometric mean length of stay of 24.5 days and an arithmetic mean of 35.5 days for FY2027. The geometric mean is used for transfer-payment calculations.
Which DRGs are in the same CC/MCC family as 001?
DRG 002 (Heart Transplant or Implant of Heart Assist System without MCC, weight 11.0040). The family's weights range from 11.0040 to 28.0830, so documented complications and comorbidities change payment materially.
What documentation supports the severity level of DRG 001?
DRG 001 requires at least one secondary diagnosis on the CMS Major Complication or Comorbidity list, documented as present and clinically addressed during the stay (monitored, evaluated, treated or extending the stay). Conditions such as acute respiratory failure, severe sepsis or acute kidney injury with specified cause qualify only when the attending's note states the diagnosis itself, not just the lab values. Recovery auditors downgrade this group to the CC or base level when the MCC rests on an unconfirmed query or a resolved historical condition, so the query response and the discharge summary must agree.
Which codes group to DRG 001?
The v44 Definitions Manual lists 4 operating room procedures codes and 56 implant of heart assist system codes for this group. Examples from the operating room procedures list: 02YA0Z0 (Transplantation of Heart, Allogeneic, Open Approach); 02YA0Z1 (Transplantation of Heart, Syngeneic, Open Approach); 02YA0Z2 (Transplantation of Heart, Zooplastic, Open Approach); 02RK0JZ (Replacement of Right Ventricle with Synthetic Substitute, Open Approach).
Is DRG 001 a post-acute transfer DRG?
No. DRG 001 is not on the FY2027 post-acute care transfer list, so the transfer per-diem policy does not apply to it.
Sources
Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-01. Verify against the primary file before billing or contracting decisions.
- IPPS FY2027 Final Rule Table 5 (CMS-1849-F)Version v44 FY2027 · effective 2026-10-01 · file CMS-1849-F Table 5.txtSHA-256 01003dd571c1e2f5…
- IPPS FY2026 Final Rule Table 5 (CMS-1833-F)Version v43 FY2026 · effective 2025-10-01 · file CMS-1833-F Table 5.txtSHA-256 bf8c390d14b3cd3e…
- ICD-10 MS-DRG Definitions Manual v44 (text)Version v44 · effective 2026-10-01 · file fy2027-fr-icd10-ms-drg-definitions-manual-files-v44.zipSHA-256 ae4f6c11727fe91f…
Disclaimer
This page is an operational reference compiled from the CMS IPPS FY2027 final rule (Table 5) and the v44 ICD-10 MS-DRG Definitions Manual. Relative weights are national factors; actual payment depends on each hospital's wage-adjusted base rate, add-ons, outliers and transfer adjustments. Nothing here is legal, clinical or billing advice; verify grouping against your encoder and the published CMS files.