I40.0Infective myocarditis

I40.0 is the ICD-10-CM diagnosis code for infective myocarditis. It belongs to category I40 (acute myocarditis), block I30-I5A (other forms of heart disease) and chapter 9 (diseases of the circulatory system). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within I40 (acute myocarditis), I40.0 is specifically for infective myocarditis. Related codes cover isolated myocarditis (I40.1), other acute myocarditis (I40.8) and unspecified (I40.9).

Use an additional code (B95-B97) to identify infectious agent.

As a secondary diagnosis it is an MCC (major complication or comorbidity), which can move an inpatient stay into the highest-paying "with MCC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 314 (Other Circulatory System Diagnoses with MCC, relative weight 2.0873), DRG 315 (Other Circulatory System Diagnoses with CC, relative weight 0.9508), DRG 316 (Other Circulatory System Diagnoses without CC/MCC, relative weight 0.6677), DRG 791 (Prematurity with Major Problems, relative weight 4.1075), DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), DRG 974 (HIV with Major Related Condition with MCC, relative weight 3.0506) and 2 more, in MDC 05 (Diseases and Disorders of the Circulatory System), MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period) and MDC 25 (Human Immunodeficiency Virus Infections), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 422.91 (idiopathic myocarditis) and 422.92 (septic myocarditis).