ICD-10 code for acute or subacute endocarditis

The ICD-10-CM code for acute or subacute endocarditis is I33.9 (Acute and subacute endocarditis, unspecified). The official index lists 3 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on I33.9.

Within I33, choose I33.9 (unspecified) only when documentation doesn't support a more specific option: infective endocarditis (I33.0).

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 288 (Acute and Subacute Endocarditis with MCC, relative weight 2.6315), DRG 289 (Acute and Subacute Endocarditis with CC, relative weight 1.5362), DRG 290 (Acute and Subacute Endocarditis without CC/MCC, relative weight 0.8367), 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.