2027 ICD-10-CM Diagnosis Code I49.9Cardiac arrhythmia, unspecified
ICD-10-CM Codes›I00–I99›I30-I5A›I49
- Billable — Valid for Submission
- Chronic Condition
I49.9 is a billable ICD-10-CM diagnosis code for cardiac arrhythmia, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 308 through 310. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac dysrhythmias.
This medical diagnosis code is frequently used in Cardiology medical specialties to designate conditions such cardiac arrhythmias (other).
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Abnormal heart beat
- Arrhythmia due to and following acute myocardial infarction
- Arrhythmia due to vegetation of infective endocarditis
- Atypical Timothy syndrome
- Cardiac arrhythmia
- Cardiac arrhythmia associated with genetic disorder
- Cardiac arrhythmia due to coronary artery spasm
- Cardiac arrhythmia during pregnancy
- Cardiac arrhythmia in mother complicating childbirth
- Cardiac channelopathy
- EKG: ventricular arrhythmia
- Fibrillation
- Finding of regularity of heart rhythm
- GNB5-related intellectual disability, cardiac arrhythmia syndrome
- Heart disease in mother complicating childbirth
- Heart disease in mother complicating pregnancy, childbirth AND/OR puerperium
- Heart irregularly irregular
- Heart regularly irregular
- Irregular heart beat
- Postoperative cardiac arrhythmia
- Recurrent encephalopathy
- Recurrent metabolic encephalomyopathic crises, rhabdomyolysis, cardiac arrhythmia, intellectual disability syndrome
- Sudden arrhythmic death syndrome
- Sudden cardiac death
- Supraventricular arrhythmia
- Timothy syndrome
- Ventricular arrhythmia
- Withdrawal arrhythmia
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to I49.9: its own notes plus those printed at I49 and Chapter 9. A note printed at a category, block or chapter applies to every code under it.
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Arrhythmia (cardiac) NOS
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
- systemic connective tissue disorders (M30-M36)
- transient cerebral ischemic attacks and related syndromes (G45.-)
Code First
The underlying condition named in the note is sequenced before this code.
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Disorder (of) See Also: Disease;
heart action I49.9
Disturbance (s) See Also: Disease;
rhythm, heart I49.9
cardiac I49.9
disorder I49.9
escape I49.9
heart, abnormal I49.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Arrhythmias, Cardiac
any disturbances of the normal rhythmic beating of the heart or myocardial contraction. cardiac arrhythmias can be classified by the abnormalities in heart rate, disorders of electrical impulse generation, or impulse conduction.
Patient EducationClinical
Arrhythmia
An arrhythmia is a problem with the rate or rhythm of your heartbeat. Your heart beats too quickly, too slowly, or with an irregular pattern. Changes in the electrical signals that control your heartbeat cause arrhythmias.
The full article covers:
- What is an arrhythmia?
- What causes an arrhythmia?
- What are the symptoms of an arrhythmia?
- How is an arrhythmia diagnosed?
- What are the treatments for an arrhythmia?
- Can arrhythmias be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert I49.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About I49.9Overview
What is the ICD-10 code for cardiac arrhythmia, unspecified?
The ICD-10-CM code for cardiac arrhythmia, unspecified is I49.9 (sometimes written as I499). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is I49.9 (Other cardiac arrhythmias) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report cardiac arrhythmia, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does I49.9 group to?
When cardiac arrhythmia, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 309, 310, 308, with relative weights from 0.5686 to 1.1809 depending on complications. Higher weights mean higher Medicare reimbursement.
What is coded first with I49.9?
The Code First note at I49, which applies to I49.9, reads: cardiac arrhythmia complicating: abortion or ectopic or molar pregnancy (O00-O07, O08.8); obstetric surgery and procedures (O75.4). When one of these applies, it is sequenced before I49.9.
What is the ICD-9 equivalent of I49.9?
Under the General Equivalence Mappings, cardiac arrhythmia, unspecified converts to ICD-9-CM 427.9 (cardiac dysrhythmia NOS). The mapping is a direct match.
