2026 ICD-10-CM Diagnosis Code R94.31Abnormal electrocardiogram [ECG] [EKG]

ICD-10-CM Codes›R00–R99›R90-R94›R94

ICD-10-CM R94.31
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

R94.31 is a billable ICD-10-CM diagnosis code for abnormal electrocardiogram [ECG] [EKG]. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 314 through 316. As a symptom code, it should not be used as a principal diagnosis once a related definitive diagnosis has been established. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Abnormal findings without diagnosis.

Code Identity

ICD-10-CM Code
R94.31
Billable Status
Yes — Valid for Submission
Code Describes
Abnormal electrocardiogram [ECG] [EKG]
Short Description
Abnormal electrocardiogram [ECG] [EKG]
Same as the full description in the CMS dataset.
Parent Code
R94.3
Abnormal results of cardiovascular function studies

Code Classification

ChapterR00–R99Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
SectionR90-R94Abnormal findings on diagnostic imaging and in function studies, without diagnosis
CategoryR94Abnormal results of function studies
This CodeR94.31Abnormal electrocardiogram [ECG] [EKG]

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Ambulatory ECG abnormal
  • Anterior and lateral ST segment elevation
  • Anterior myocardial infarction on electrocardiogram
  • Anterior ST segment depression
  • Anterior ST segment elevation
  • Anterior T wave inversion
  • Anterolateral infarction by electrocardiogram
  • Anteroseptal infarction on electrocardiogram
  • Atrial hypertrophy by EKG
  • Atrioventricular conduction pattern - finding
  • Bifid P wave
  • Bifid T wave
  • Bifid U wave
  • Borderline abnormal ECG
  • Brugada electrocardiograph pattern
  • Cardiac conduction pattern - finding
  • Cardiac pacemaker active on electrocardiogram
  • Clockwise cardiac rotation
  • Counterclockwise cardiac rotation
  • Counterclockwise vectorcardiographic loop
  • Decreased electrocardiogram voltage
  • Deep S wave
  • Deep symmetric anterior T wave inversion
  • Diffuse ST segment depression
  • Digitalis toxicity by EKG
  • Diminished LV forces by EKG
  • Diminished RV forces by EKG
  • ECG artifact
  • ECG voltage - finding
  • ECG: atrial fibrillation
  • ECG: bradycardia
  • ECG: ectopic beats
  • ECG: ectopic beats - premature atrial contraction
  • ECG: ectopic beats - unifocal premature ventricular contractions
  • ECG: ectopic beats with multifocal premature ventricular contractions
  • ECG: extrasystole
  • ECG: F wave - finding
  • ECG: F wave absent
  • ECG: idioventricular rhythm
  • ECG: junctional rhythm
  • ECG: junctional tachycardia
  • ECG: paced rhythm
  • ECG: paroxysmal ventricular tachycardia
  • ECG: partial atrioventricular block - 2:1
  • ECG: partial atrioventricular block - 3:1
  • ECG: partial atrioventricular block - long PR
  • ECG: partial sinoatrial block
  • ECG: premature ventricular contractions
  • ECG: pulseless electrical activity
  • ECG: Q-T interval abnormal
  • ECG: sinus arrhythmia
  • ECG: sinus bradycardia
  • ECG: sinus rhythm
  • ECG: sinus tachycardia
  • ECG: ST interval abnormal
  • ECG: U wave exaggerated
  • ECG: ventricular ectopics
  • EKG axis perpendicular to frontal plane
  • EKG hypertrophy
  • EKG myocardial ischemia
  • EKG ST segment changes
  • EKG ventricular tachycardia monomorphic
  • EKG ventricular tachycardia polymorphic
  • EKG: accelerated junctional rhythm
  • EKG: asystole
  • EKG: atrial ectopics
  • EKG: atrial flutter
  • EKG: atrial tachycardia
  • EKG: focal atrial tachycardia
  • EKG: heart block
  • EKG: junctional escape rhythm
  • EKG: left bundle branch block
  • EKG: left ventricular strain
  • EKG: multifocal atrial tachycardia
  • EKG: myocardial infarction
  • EKG: P wave abnormal
  • EKG: P-R interval abnormal
  • EKG: Q wave abnormal
  • EKG: QRS complex abnormal
  • EKG: R wave abnormal
  • EKG: right bundle branch block
  • EKG: right ventricle hypertrophy
  • EKG: S wave abnormal
  • EKG: supraventricular arrhythmia
  • EKG: supraventricular tachycardia
  • EKG: T wave abnormal
  • EKG: torsades de pointes
  • EKG: U wave abnormal
  • EKG: ventricular arrhythmia
  • EKG: ventricular fibrillation
  • EKG: ventricular tachycardia
  • EKG:left ventricle hypertrophy
  • EKG:posterior/inferior infarct
  • Electrical alternation of heart
  • Electrocardiogram abnormal
  • Electrocardiogram showing electrical capture following temporary pacing
  • Electrocardiogram showing paced rhythm with electrical capture
  • Electrocardiogram: paroxysmal atrial tachycardia
  • Finding of TU interval
  • Flat U wave
  • Flattened P wave
  • Flattened T wave
  • Flattened U wave
  • High T-voltage
  • Inadequate ECG tracing
  • Inferior and lateral ST segment elevation
  • Inferior and right sided ST segment elevation
  • Inferior myocardial infarction on electrocardiogram
  • Inferior ST segment depression
  • Inferior ST segment elevation
  • Inverted biphasic anterior T wave
  • Inverted P wave
  • Inverted T wave
  • Inverted U wave
  • Lateral infarction on electrocardiogram
  • Lateral ST segment elevation
  • Left atrial hypertrophy by EKG
  • Left axis deviation
  • Left axis deviation greater than -90 degrees by EKG
  • Left ventricular hypertrophy by electrocardiogram
  • Left ventricular ST changes
  • Low QRS voltages
  • Low QRS voltages in the limb leads
  • Low QRS voltages in the precordial leads
  • Low U wave
  • Low ventricular voltage by EKG
  • Narrow QRS complex
  • Nonspecific ST-T abnormality on electrocardiogram
  • P mitrale
  • P pulmonale
  • P wave - finding
  • P wave axis - finding
  • P wave axis superior
  • P wave left axis deviation
  • P wave right axis deviation
  • Paired ventricular premature complexes on electrocardiogram
  • Pathological Q wave
  • Posterior myocardial infarction on electrocardiogram
  • Posterior ST segment depression
  • Posterior ST segment elevation
  • PR depression
  • PR elevation
  • PR interval - finding
  • Prolonged P wave
  • Prolonged PR interval
  • Prolonged ST segment
  • Prolonged T wave
  • Prolonged TU interval
  • Prolonged U wave
  • Provoked Brugada electrocardiograph pattern
  • Q wave - finding
  • Q wave height decreased
  • Q wave height increased
  • QRS Axis - finding
  • QRS complex - finding
  • QRS complex dropped
  • QRS complex height decreased
  • QRS complex height increased
  • QT interval - finding
  • Quinidine toxicity by EKG
  • R wave - finding
  • R wave height decreased
  • R wave height increased
  • Reverse tick ST segment
  • Right atrial hypertrophy by electrocardiogram
  • Right axis deviation
  • Right ventricular ST changes
  • rSr pattern in V1 and V2
  • S wave - finding
  • S wave height decreased
  • S wave height increased
  • Secondary ST-T abnormality on electrocardiogram
  • Septal infarction by electrocardiogram
  • Shortened P wave
  • Shortened PR interval
  • Shortened QT interval
  • Shortened ST interval
  • Shortened ST segment
  • Shortened T wave
  • Shortened TU interval
  • Shortened U wave
  • Sloping PR interval
  • Sloping ST segment
  • ST segment depression
  • ST segment elevation
  • Superior axis
  • T wave alternans on electrocardiogram
  • T wave duration - finding
  • Tall P wave
  • Tall R wave
  • Tall T wave
  • Tall tented T wave
  • Tall U wave
  • TU depression
  • TU elevation
  • Type A Wolff-Parkinson-White pattern
  • Type B Wolff-Parkinson-White pattern
  • Ventricular escape rhythm on electrocardiogram
  • Ventricular hypertrophy by EKG
  • Ventricular inversion electrocardiogram pattern
  • Wide QRS complex

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Type 1 Excludes

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Abnormal, abnormality, abnormalities
      • electrocardiogram [ECG] [EKG]
    • Prolonged, prolongation(of)
      • QT interval

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR SYM017
Abnormal findings without diagnosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Heart Health Tests

Heart diseases are the number one killer in the United States. They are also a major cause of disability. If you do have heart disease, it is important to find it early, when it is easier to treat. Blood tests and heart health tests can help find heart diseases or identify problems that can lead to heart diseases.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert R94.31 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
794.31 Abnorm electrocardiogram
Exact Match The mapping is direct, with no qualifiers.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About R94.31Overview

Is R94.31 (Abnormal results of cardiovascular function studies) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report abnormal electrocardiogram [ECG] [EKG] on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does R94.31 group to?

When abnormal electrocardiogram [ECG] [EKG] is the principal diagnosis on an inpatient stay, it groups to MS-DRG 314, 315, 316, with relative weights from 0.6821 to 2.0852 depending on complications. Higher weights mean higher Medicare reimbursement.

Can R94.31 be a principal diagnosis?

Use it with care. This is a symptom code, so once a definitive diagnosis explaining the abnormal electrocardiogram [ECG] [EKG] is established, that condition takes the principal position instead.

What is the ICD-9 equivalent of R94.31?

Under the General Equivalence Mappings, abnormal electrocardiogram [ECG] [EKG] converts to ICD-9-CM 794.31 (abnorm electrocardiogram). The mapping is a direct match.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.