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ICD-10-CM I44.0: Atrioventricular block, first degree

I44.0 is the billable ICD-10-CM code for atrioventricular block, first degree, in category I44 (Atrioventricular and left bundle-branch block) of the Other forms of heart disease section. As a principal diagnosis it groups to MS-DRG 308 Cardiac Arrhythmia and Conduction Disorders with MCC, MS-DRG 309 Cardiac Arrhythmia and Conduction Disorders with CC, MS-DRG 310 Cardiac Arrhythmia and Conduction Disorders without CC/MCC (MDC 05 MDC 05: Diseases and Disorders of the Circulatory System). 27 LCD billing and coding articles list it as covered.

Compiled from CMS files by the QuickIntell RCM Editorial Team · Data effective · Method: reference methodology · Report a data correction

Data currency: ICD-10-CM code descriptions: FY2027 (effective October 1, 2026); IPPS Table 5 (MS-DRG weights): v44 FY2027 (final rule + CN3) (effective October 1, 2026); ICD-10-CM to HCC mapping: PY2027 initial ICD-10-CM mappings (dates of service 2026) (payment year 2027); Medicare Coverage Database billing and coding articles: MCD release October 8, 2026 (effective October 4, 2026). Next CMS release: FY2028 code files, effective October 1, 2027 for the ICD-10-CM code descriptions; FY2028 final rule (August 2027), effective October 1, 2027; an April 1 interim grouper update when CMS issues one for the IPPS Table 5 (MS-DRG weights); PY2028 advance notice (February 2027) and the PY2027 midyear final mapping (spring 2027) for the ICD-10-CM to HCC mapping; weekly, every Thursday for the Medicare Coverage Database billing and coding articles.

Code
I44.0
billable FY2027 ICD-10-CM code
Category
I44 Atrioventricular and left bundle-branch block
Chapter
9: Diseases of the circulatory system (I00-I99)
CC/MCC (MS-DRG v44)
Neither
CMS-HCC V28
Not mapped
POA reporting
Required

Tabular list notes for I44.0

The tabular list has no notes on I44.0 itself; the notes below apply from its parent headings.

MS-DRG grouping when I44.0 is the principal diagnosis

MS-DRG v44 groups for I44.0 as principal diagnosis
MDCMS-DRGs
05 MDC 05: Diseases and Disorders of the Circulatory System308309310

The final group also depends on procedures, secondary diagnoses and discharge status; the MS-DRG lookup for I44.0 shows the full grouping logic.

CC/MCC status and inpatient edits

I44.0 is neither a CC nor an MCC under MS-DRG v44, so as a secondary diagnosis it does not raise the MS-DRG severity level. Check I44.0 against a principal diagnosis.

  • Present on admission: a POA indicator is required on inpatient claims.

CMS-HCC V28 risk adjustment

I44.0 does not map to a payment HCC in the PY2027 CMS-HCC V28 model, so on its own it does not change a Medicare Advantage risk score.

LCD billing and coding articles that list I44.0

27 current Medicare billing and coding articles list I44.0 among the diagnoses that support medical necessity for the services they cover.

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Frequently asked questions

What does ICD-10-CM I44.0 mean?

I44.0 means atrioventricular block, first degree. It is one of 10 billable codes under I44, atrioventricular and left bundle-branch block.

Which MS-DRG does I44.0 group to?

As the principal diagnosis, I44.0 groups to MS-DRG 308 Cardiac Arrhythmia and Conduction Disorders with MCC, MS-DRG 309 Cardiac Arrhythmia and Conduction Disorders with CC, MS-DRG 310 Cardiac Arrhythmia and Conduction Disorders without CC/MCC (MDC 05 MDC 05: Diseases and Disorders of the Circulatory System) under MS-DRG v44, before procedures and secondary diagnoses are applied.

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-10. Verify against the primary file before billing or contracting decisions. The reference methodology explains how each figure is computed from these files.

Disclaimer

The descriptor and notes are reproduced from the FY2027 ICD-10-CM files; MS-DRG, CC/MCC and HCC facts come from the CMS FY2027 and PY2027 tables. Code from the medical record and the ICD-10-CM Official Guidelines. Not legal, clinical or billing advice.

Found a figure that does not match the CMS file? Report a data correction with the CMS file and the value you expected; the request reaches the editorial team through the contact form.