I39Endocarditis and heart valve disorders in diseases classified elsewhere

I39 is the ICD-10-CM diagnosis code for endocarditis and heart valve disorders in diseases classified elsewhere. It belongs to 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.

Don't report I39 together with the conditions in its Excludes1 note: candidiasis (B37.6), gonococcal infection (A54.83), Libman-Sacks disease (M32.11), listerosis (A32.82) and 5 more.

Code first underlying disease, such as: Q fever (A78).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" 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 306 (Cardiac Congenital and Valvular Disorders with MCC, relative weight 1.546), DRG 307 (Cardiac Congenital and Valvular Disorders without MCC, relative weight 0.9148), DRG 791 (Prematurity with Major Problems, relative weight 4.1075) and DRG 793 (Full Term Neonate with Major Problems, relative weight 4.2195), in MDC 05 (Diseases and Disorders of the Circulatory System) and MDC 15 (Newborns and Other Neonates with Conditions Originating in the Perinatal Period), 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 is a manifestation code, so it describes the effect of an underlying disease and can't be the principal diagnosis. Code the underlying condition first.

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 421.1 (acute and subacute infective endocarditis in diseases classified elsewhere) and 424.91 (endocarditis in diseases classified elsewhere).