2026 ICD-10-CM Diagnosis Code T46.2X4APoisoning by other antidysrhythmic drugs, undetermined, initial encounter
T46.2X4A is a billable ICD-10-CM diagnosis code for poisoning by other antidysrhythmic drugs, undetermined, initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, undetermined; External cause codes: poisoning by drug; and Poisoning by drugs, initial encounter.
Code Identity
Code Classification
Coding GuidelinesGuidance
When coding a poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration), first assign the appropriate code from categories T36-T50. The poisoning codes have an associated intent as their 5th or 6th character (accidental, intentional self-harm, assault and undetermined). If the intent of the poisoning is unknown or unspecified, code the intent as accidental intent. The undetermined intent is only for use if the documentation in the record specifies that the intent cannot be determined. Use additional code(s) for all manifestations of poisonings.
The appropriate 7th character is to be added to each code from block Poisoning by, adverse effect of and underdosing of agents primarily affecting the cardiovascular system (T46). Use the following options for the applicable episode of care:
- A - initial encounter
- D - subsequent encounter
- S - sequela
Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Ajmaline
an alkaloid found in the root of rauwolfia serpentina, among other plant sources. it is a class 1-a antiarrhythmic agent that apparently acts by changing the shape and threshold of cardiac action potentials.Amiodarone
an antianginal and class iii antiarrhythmic drug. it increases the duration of ventricular and atrial muscle action by inhibiting potassium channels and voltage-gated sodium channels. there is a resulting decrease in heart rate and in vascular resistance.Aprindine
a class ib anti-arrhythmia agent used to manage ventricular and supraventricular arrhythmias.Bunaftine
n-butyl-n-(2-(diethylamino)ethyl)-1-naphthamide. a proposed antiarrhythmic that prolongs myocardial refractory period and stabilizes cell membranes.Disopyramide
a class i anti-arrhythmic agent (one that interferes directly with the depolarization of the cardiac membrane and thus serves as a membrane-stabilizing agent) with a depressant action on the heart similar to that of guanidine. it also possesses some anticholinergic and local anesthetic properties.Encainide
one of the anti-arrhythmia agents, it blocks voltage-gated sodium channels and slows conduction within the his-purkinje system and myocardium.Flecainide
a potent anti-arrhythmia agent, effective in a wide range of ventricular and atrial arrhythmias and tachycardias.Lorajmine
a monochloroacetyl derivative of ajmaline. it is a class ia antiarrhythmic agent that is rapidly hydrolyzed to ajmaline by plasma and tissue esterases.Mexiletine
antiarrhythmic agent pharmacologically similar to lidocaine. it may have some anticonvulsant properties.Procainamide
a class ia antiarrhythmic drug that is structurally-related to procaine.Propafenone
an antiarrhythmia agent that is particularly effective in ventricular arrhythmias. it also has weak beta-blocking activity.Quinidine
an optical isomer of quinine, extracted from the bark of the chinchona tree and similar plant species. this alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. it prolongs cellular action potentials, and decreases automaticity. quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.Tocainide
an antiarrhythmic agent which exerts a potential- and frequency-dependent block of sodium channels.
Table of Drugs and ChemicalsClinical
Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.
Patient EducationClinical
Poisoning
A poison is any substance that is harmful to your body. You might swallow it, inhale it, inject it, or absorb it through your skin. Any substance can be poisonous if too much is taken. Poisons can include:
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert T46.2X4A to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About T46.2X4AOverview
Is T46.2X4A (Poisoning by other antidysrhythmic drugs, undetermined) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report poisoning by other antidysrhythmic drugs, undetermined, initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What does the 7th character A in T46.2X4A mean?
The final character A marks the initial encounter: use it while the patient is receiving active treatment for poisoning by other antidysrhythmic drugs, undetermined, such as an emergency visit or first evaluation.
What MS-DRG does T46.2X4A group to?
When poisoning by other antidysrhythmic drugs, undetermined, initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of T46.2X4A?
Under the General Equivalence Mappings, poisoning by other antidysrhythmic drugs, undetermined, initial encounter converts to ICD-9-CM 972.0 (pois-card rhythm regulat) and E980.4 (undet pois-med agnt NEC). The mapping is approximate, so confirm the match fits the documentation.
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.
