I47.21 ICD-10-CM Code: Torsades de pointes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I47.21 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on I47.21 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for I47.21

MedCoder structured workflow — derived from this code’s own official record

Before you code I47.21

1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I47.21. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in I47.21’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewR00.0

2. Is the underlying (etiologic) condition the Code First note names documented?
   Yes → Sequence the underlying condition first, then I47.21.
   No → Continue; do not add an underlying condition the record does not document.

   ReviewO08.8, O75.4

Consider I47.21. Then work the Use Additional Code note and review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

The underlying (etiologic) condition

Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).

The conditions the Use Additional Code note names

Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.

Official instructions as workflow

• Excludes1 — check before selecting I47.21(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I47.21: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareR00.0

  See the official tabular notes · Guidelines I.A.12.a

• Code First — sequencing check(3 notes)

  Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before I47.21. Do not add an underlying condition the record does not document.

  ReviewO08.8, O75.4

  See the official tabular notes · Guidelines I.A.13

• Use Additional Code — after identifying I47.21(1 note)

  Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with I47.21 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

  See the official tabular notes · Guidelines I.A.13

• Code Also — related condition(1 note)

  Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

  ReviewI45.81

  See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Torsades de pointes

Don’t confuse I47.21 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of I47.21 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• R00.0— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of tachycardia NOS moves the case to R00.0; the two are not reported together unless documented as unrelated.

  Full comparison: I47.21 vs R00.0 →

• I47.20— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Ventricular tachycardia, unspecified” takes I47.20; specificity in the record moves it back here.

  Full comparison: I47.21 vs I47.20 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

1. Sequencing: 3 Code First instructions — the underlying condition is sequenced before this code when present. See the Code First notes
2. 1 Use Additional Code instruction — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
3. 1 Code Also note — a second code may apply; the guidelines leave its sequencing to the circumstances of the encounter. See the Code Also notes
4. 3 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name I47.21 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: R00.0 — Tachycardia, unspecified (via I47.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: R00 — Abnormalities of heart beat (via I47.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 2 Code First instructions: I21.A1 — Myocardial infarction type 2, I5A — Non-ischemic myocardial injury (non-traumatic) (via I47.-).

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

Referenced by 1 Use Additional Code instruction: G90.81 — Serotonin syndrome (via I47.2.-).

These codes instruct coders to additionally report this code when it applies.

Referenced by 1 Code Also instruction: M35.81 — Multisystem inflammatory syndrome (via I47.-).

These codes suggest coding this condition alongside when both are present.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 51 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 308 (MDC 05), DRG 309 (MDC 05), DRG 310 (MDC 05), DRG 791 (MDC 15), DRG 793 (MDC 15).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):CIR017 — Cardiac dysrhythmias (default).

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

I45.6 — Pre-excitation syndrome, I45.81 — Long QT syndrome, I45.89 — Other specified conduction disorders, I45.9 — Conduction disorder, unspecified, I46.9 — Cardiac arrest, cause unspecified, I47.0 — Re-entry ventricular arrhythmia, I47.10 — Supraventricular tachycardia, unspecified, I47.11 — Inappropriate sinus tachycardia, so stated, I47.19 — Other supraventricular tachycardia, I47.20 — Ventricular tachycardia, unspecified, I47.29 — Other ventricular tachycardia, I47.9 — Paroxysmal tachycardia, unspecified, I48.0 — Paroxysmal atrial fibrillation, I48.11 — Longstanding persistent atrial fibrillation, I48.19 — Other persistent atrial fibrillation, I48.20 — Chronic atrial fibrillation, unspecified, I48.21 — Permanent atrial fibrillation, I48.3 — Typical atrial flutter, I48.4 — Atypical atrial flutter, I48.91 — Unspecified atrial fibrillation, +30 more

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Specified Heart Arrhythmias) for risk-adjusted payment.

I44.2 — Atrioventricular block, complete, I47.0 — Re-entry ventricular arrhythmia, I47.20 — Ventricular tachycardia, unspecified, I47.29 — Other ventricular tachycardia, I47.9 — Paroxysmal tachycardia, unspecified, I48.0 — Paroxysmal atrial fibrillation, I48.11 — Longstanding persistent atrial fibrillation, I48.19 — Other persistent atrial fibrillation, I48.20 — Chronic atrial fibrillation, unspecified, I48.21 — Permanent atrial fibrillation, I48.3 — Typical atrial flutter, I48.4 — Atypical atrial flutter, I48.91 — Unspecified atrial fibrillation, I48.92 — Unspecified atrial flutter, I49.2 — Junctional premature depolarization, I49.5 — Sick sinus syndrome

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Cardiac dysrhythmias).

I47.0 — Re-entry ventricular arrhythmia, I47.1 — Supraventricular tachycardia, I47.10 — Supraventricular tachycardia, unspecified, I47.11 — Inappropriate sinus tachycardia, so stated, I47.19 — Other supraventricular tachycardia, I47.2 — Ventricular tachycardia, I47.20 — Ventricular tachycardia, unspecified, I47.29 — Other ventricular tachycardia, I47.9 — Paroxysmal tachycardia, unspecified, I48.0 — Paroxysmal atrial fibrillation, I48.1 — Persistent atrial fibrillation, I48.11 — Longstanding persistent atrial fibrillation, I48.19 — Other persistent atrial fibrillation, I48.2 — Chronic atrial fibrillation, I48.20 — Chronic atrial fibrillation, unspecified, I48.21 — Permanent atrial fibrillation, I48.3 — Typical atrial flutter, I48.4 — Atypical atrial flutter, I48.91 — Unspecified atrial fibrillation, I48.92 — Unspecified atrial flutter, +8 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Iron Panel, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of I47.21 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run I47.21 with these 15 related codes in Claim Check

Hierarchy

• I00-I99 — Chapter 9: Diseases of the Circulatory System (I00-I99) (I00-I99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I30-I5A — Other forms of heart disease[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Use Additional Code (15)

• T36 — Poisoning by, adverse effect of and underdosing of systemic antibiotics[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T37 — Poisoning by, adverse effect of and underdosing of other systemic anti-infectives and antiparasitics[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T38 — Poisoning by, adverse effect of and underdosing of hormones and their synthetic substitutes and antagonists, not elsewhere classified[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T39 — Poisoning by, adverse effect of and underdosing of nonopioid analgesics, antipyretics and antirheumatics[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T40 — Poisoning by, adverse effect of and underdosing of narcotics and psychodysleptics [hallucinogens][Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T41 — Poisoning by, adverse effect of and underdosing of anesthetics and therapeutic gases[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T42 — Poisoning by, adverse effect of and underdosing of antiepileptic, sedative- hypnotic and antiparkinsonism drugs[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• T43 — Poisoning by, adverse effect of and underdosing of psychotropic drugs, not elsewhere classified[Use Additional Code]: “code for adverse effect, if applicable, to identify drug (T36-T50 with fifth or sixth character 5)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• and 7 more

Code Also

• I45.81 — Long QT syndrome[Code Also]: “, if applicable, long QT syndrome (I45.81)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes

• R00.0 — Tachycardia, unspecified[Excludes1](via I47.-): “paroxysmal tachycardia (I47.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes2 notes

• R00 — Abnormalities of heart beat[Excludes2](via I47.-): “specified arrhythmias (I47-I49)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code First instructions

• I21.A1 — Myocardial infarction type 2[Code First]: “paroxysmal tachycardia (I47.0-I47.9)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026
• I5A — Non-ischemic myocardial injury (non-traumatic)[Code First](via I47.-): “paroxysmal tachycardia (I47.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Use Additional Code instructions

• G90.81 — Serotonin syndrome[Use Additional Code](via I47.2.-): “ventricular tachycardia (I47.2-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Code Also instructions

• M35.81 — Multisystem inflammatory syndrome[Code Also](via I47.-): “cardiac arrhythmia (I47-I49.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• CIR017 — Cardiac dysrhythmias[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Risk adjustment (CMS-HCC)

• HCC 238 — Specified Heart Arrhythmias [CMS-HCC]— CMS-HCC V28 · 2026

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 308 — CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITH MCC[MS-DRG]: “CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITH MCC (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 309 — CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITH CC[MS-DRG]: “CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITH CC (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 310 — CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITHOUT CC/MCC[MS-DRG]: “CARDIAC ARRHYTHMIA AND CONDUCTION DISORDERS WITHOUT CC/MCC (MDC 05)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 05 — Diseases and Disorders of the Circulatory System[MDC crossing]: “Diseases and Disorders of the Circulatory System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 17,209 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Torsades de pointes[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (11)

• I47 — Paroxysmal tachycardia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.0 — Re-entry ventricular arrhythmia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.1 — Supraventricular tachycardia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.10 — Supraventricular tachycardia, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.11 — Inappropriate sinus tachycardia, so stated[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.19 — Other supraventricular tachycardia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.2 — Ventricular tachycardia[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• I47.20 — Ventricular tachycardia, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 3 more

Change history

• FY2023 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2023

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Risk adjustment Official source data

2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to I47.21 in its code family, with their registry titles.

• I47.0 — Re-entry ventricular arrhythmia
• I47.1 — Supraventricular tachycardia
• I47.10 — Supraventricular tachycardia, unspecified
• I47.11 — Inappropriate sinus tachycardia, so stated
• I47.19 — Other supraventricular tachycardia
• I47.2 — Ventricular tachycardia
• I47.20 — Ventricular tachycardia, unspecified
• I47.22 — Catecholaminergic polymorphic ventricular tachycardia [CPVT]
• I47.29 — Other ventricular tachycardia
• I47.9 — Paroxysmal tachycardia, unspecified

View all codes in the I47 family