2026 ICD-10-CM Diagnosis Code R94.31
Abnormal electrocardiogram [ECG] [EKG]
- ICD-10-CM Code:
- R94.31
- ICD-10 Code for:
- Abnormal electrocardiogram [ECG] [EKG]
- Is Billable?
- Yes - Valid for Submission
- Chronic Condition Indicator: [1]
- Not chronic
- Code Navigator:
R94.31 is a billable diagnosis code used to specify a medical diagnosis of abnormal electrocardiogram [ecg] [ekg]. The code is valid during the current fiscal year for the submission of HIPAA-covered transactions from October 01, 2025 through September 30, 2026.
According to ICD-10-CM guidelines this code should not to be used as a principal diagnosis code when a related definitive diagnosis has been established.
Approximate Synonyms
The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.
- 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
- Atrial hypertrophy by EKG
- Atrioventricular conduction pattern - finding
- Atrioventricular conduction pattern - finding
- Bifid P wave
- Bifid T wave
- Bifid U wave
- Borderline abnormal ECG
- Brugada electrocardiograph pattern
- Cardiac conduction pattern - finding
- Cardiac conduction pattern - finding
- 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 voltage - finding
- ECG voltage - finding
- ECG voltage - finding
- ECG: atrial fibrillation
- ECG: bradycardia
- ECG: ectopic beats
- ECG: ectopic beats
- ECG: ectopic beats
- 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 rhythm
- 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: myocardial infarction
- EKG: myocardial infarction
- EKG: myocardial infarction
- EKG: myocardial infarction
- EKG: myocardial infarction
- EKG: myocardial infarction
- 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 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: ventricular tachycardia
- 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
- Finding of TU interval
- Finding of TU interval
- 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 - finding
- P wave - finding
- P wave - finding
- P wave - finding
- P wave - finding
- P wave - finding
- P wave - finding
- P wave - finding
- P wave axis - finding
- P wave axis - 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
- PR interval - finding
- PR interval - finding
- PR interval - finding
- PR interval - finding
- 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 - finding
- Q wave - finding
- Q wave - finding
- Q wave height decreased
- Q wave height increased
- QRS Axis - finding
- QRS Axis - finding
- QRS Axis - finding
- QRS Axis - finding
- QRS Axis - finding
- QRS complex - finding
- QRS complex - finding
- QRS complex - finding
- QRS complex - finding
- QRS complex - finding
- QRS complex - finding
- QRS complex dropped
- QRS complex height decreased
- QRS complex height increased
- QT interval - finding
- QT interval - finding
- Quinidine toxicity by EKG
- R wave - finding
- R wave - finding
- R wave - finding
- 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 - finding
- S wave - finding
- 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
Clinical Classification
Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.
They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.
Abnormal findings without diagnosis
CCSR Code: SYM017
Inpatient Default: Y - Yes, default inpatient assignment for principal diagnosis or first-listed diagnosis.
Outpatient Default: Y - Yes, default outpatient assignment for principal diagnosis or first-listed diagnosis.
Tabular List of Diseases and Injuries
The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.
Type 1 Excludes
Type 1 ExcludesA type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
- long QT syndrome I45.81
Index to Diseases and Injuries References
The following annotation back-references for this diagnosis code are found in the injuries and diseases index. The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10-CM code(s).
- Abnormal, abnormality, abnormalities - See Also: Anomaly;
- electrocardiogram [ECG] [EKG] - R94.31
- Prolonged, prolongation (of)
- QT interval - R94.31
Index of External Cause of Injuries
References found for this diagnosis code in the External Cause of Injuries Index:
- Abnormal, abnormality, abnormalities
- electrocardiogram [ECG] [EKG]
- Prolonged, prolongation(of)
- QT interval
Convert R94.31 to ICD-9-CM
Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.
Abnorm electrocardiogram
ICD-9-CM: 794.31
This is a direct match with no additional mapping qualifiers. The absence of a flag generally means the mapping is considered exact or precise. In other words, the ICD-10 code maps cleanly to the ICD-9 code without qualification, approximation, or needing multiple codes.
Patient Education
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. There are several different types of heart health tests. Your health care provider will decide which test or tests you need, based on your symptoms (if any), risk factors, and medical history.
Cardiac Catheterization
Cardiac catheterization is a medical procedure used to diagnose and treat some heart conditions. For the procedure, your provider puts a catheter (a long, thin, flexible tube) into a blood vessel in your arm, groin, or neck, and threads it to your heart. The provider can use the catheter to:
- Do a coronary angiography. This involves putting a special type of dye in the catheter, so the dye can flow through your bloodstream to your heart. Then your provider takes x-rays of your heart. The dye allows your provider to see your coronary arteries on the x-ray, and to check for coronary artery disease (CAD). CAD is caused by plaque buildup in the arteries.
- Take samples of your blood and heart muscle.
- Examine your heart valves.
- Do procedures such as angioplasty or minor heart surgeries to repair congenital heart defects or replace heart valves.
Cardiac CT Scan
A cardiac CT (computed tomography) scan is a painless imaging test that uses x-rays to take detailed pictures of your heart and its blood vessels. Computers can combine these pictures to create a three-dimensional (3D) model of your whole heart. This test can help providers detect or evaluate various heart problems, including:
- Coronary artery disease
- Calcium buildup in the coronary arteries
- Congenital heart defects
- Problems with the aorta (the main artery that carries blood away from the heart)
- Problems with heart function and valves
- Pericardial diseases
Before you have the test, you get an injection of contrast dye. The dye highlights your heart and blood vessels in the pictures. The CT scanner is a large, tunnel-like machine. You lie still on a table that slides you into the scanner, and the scanner takes the pictures.
Cardiac MRI
Cardiac MRI (magnetic resonance imaging) is a painless imaging test that uses radio waves, magnets, and a computer to create detailed pictures of your heart. It can help your provider figure out whether you have heart disease, and if so, how severe it is. A cardiac MRI can also help your provider decide the best way to treat heart problems such as:
- Congenital heart defects
- Coronary artery disease
- Heart valve problems
- Pericarditis
- Cardiac tumors
- Damage from a heart attack
The MRI is a large, tunnel-like machine. You lie still on a table that slides you into the MRI machine. The machine makes loud noises as it takes pictures of your heart. Sometimes before the test, you might get an injection of contrast dye. The dye highlights your heart and blood vessels in the pictures.
Chest X-Ray
A chest x-ray creates pictures of the organs and structures inside your chest, such as your heart, lungs, and blood vessels. It can reveal signs of heart failure, as well as lung disorders and other causes of symptoms not related to heart disease.
Coronary Angiography
Coronary angiography (angiogram) is a procedure that uses contrast dye and x-ray pictures to look at the insides of your arteries. It can show whether plaque is blocking your arteries and how severe the blockage is. Providers use this procedure to diagnose heart diseases after chest pain, sudden cardiac arrest (SCA), or abnormal results from other heart tests such as an EKG or a stress test.
You usually have a cardiac catheterization to inject the dye into your coronary arteries. Then the provider will take special x-rays while the dye is flowing through your coronary arteries. The dye lets your provider study the flow of blood through your heart and blood vessels.
Echocardiography
Echocardiography, or echo, is a painless test that uses sound waves to create moving pictures of your heart. The pictures show the size and shape of your heart. They also show how well your heart's chambers and valves are working. Providers use an echo to diagnose many different heart problems, and to check how severe they are.
There are several different types of echocardiography. For transthoracic echocardiography (the most common type), a technician applies gel to your chest. The gel helps sound waves reach your heart. The technician moves a transducer (wand-like device) across your chest. The transducer connects to a computer. It transmits ultrasound waves into your chest, and the waves bounce (echo) back. The computer converts the echoes into pictures of your heart.
Electrocardiogram (EKG), (ECG)
An electrocardiogram, also called an ECG or EKG, is a painless test that detects and records your heart's electrical activity. It shows how fast your heart is beating and whether its rhythm is steady or irregular.
An EKG may be part of a routine exam to screen for heart disease. Or you may get it to detect and study heart problems such as heart attacks, arrhythmia, and heart failure.
For the test, you lie still on a table and a nurse or technician attaches electrodes (patches that have sensors) to the skin on your chest, arms, and legs. Wires connect the electrodes to a machine that records your heart's electrical activity.
Stress Testing
Stress testing looks at how your heart works during physical stress. It can help to diagnose coronary artery disease, and to check how severe it is. It can also check for other problems, including heart valve disease and heart failure.
For the test, you exercise (or are given medicine if you are unable to exercise) to make your heart work hard and beat fast. While this is happening, you get an EKG and blood pressure monitoring. Before or after the test, you might also have an echocardiogram, or other imaging tests such as a nuclear scan. For the nuclear scan, you get an injection of a tracer (a radioactive substance), which travels to your heart. Special cameras detect the energy from the tracer to craeate pictures of your heart. You have pictures taken after you exercise, and then after you rest.
NIH: National Heart, Lung, and Blood Institute
[Learn More in MedlinePlus]
Code History
- FY 2026 - No Change, effective from 10/1/2025 through 9/30/2026
- FY 2025 - No Change, effective from 10/1/2024 through 9/30/2025
- FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
- FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
- FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
- FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
- FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
- FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
- FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
- FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
- FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.
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.
