2021 ICD-10-CM Code I40.9

Acute myocarditis, unspecified

Version 2021

Valid for Submission

I40.9 is a billable diagnosis code used to specify a medical diagnosis of acute myocarditis, unspecified. The code I40.9 is valid during the fiscal year 2021 from October 01, 2020 through September 30, 2021 for the submission of HIPAA-covered transactions.

The ICD-10-CM code I40.9 might also be used to specify conditions or terms like acute myocarditis, interstitial myocarditis or subacute interstitial myocarditis.

Unspecified diagnosis codes like I40.9 are acceptable when clinical information is unknown or not available about a particular condition. Although a more specific code is preferable, unspecified codes should be used when such codes most accurately reflect what is known about a patient's condition. Specific diagnosis codes should not be used if not supported by the patient's medical record.

ICD-10:I40.9
Short Description:Acute myocarditis, unspecified
Long Description:Acute myocarditis, unspecified

Code Classification

Index to Diseases and Injuries

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for the code I40.9 are found in the index:

Approximate Synonyms

The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

Convert I40.9 to ICD-9 Code

Information for Patients


Cardiomyopathy

Also called: Dilated cardiomyopathy, Hypertrophic cardiomyopathy, Myocardiopathy, Restrictive cardiomyopathy

Cardiomyopathy is the name for diseases of the heart muscle. These diseases enlarge your heart muscle or make it thicker and more rigid than normal. In rare cases, scar tissue replaces the muscle tissue.

Some people live long, healthy lives with cardiomyopathy. Some people don't even realize they have it. In others, however, it can make the heart less able to pump blood through the body. This can cause serious complications, including

Heart attacks, high blood pressure, infections, and other diseases can all cause cardiomyopathy. Some types of cardiomyopathy run in families. In many people, however, the cause is unknown. Treatment might involve medicines, surgery, other medical procedures, and lifestyle changes.

NIH: National Heart, Lung, and Blood Institute


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Code History

  • 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 (First year ICD-10-CM implemented into the HIPAA code set)