Home > 2006 ICD-9-CM Diagnosis Codes > Diseases Of The Circulatory System 390-459 > Other Forms Of Heart Disease 420-429 > Acute and subacute endocarditis 421-
Specific code 2006 ICD-9-CM Diagnosis Code 421.9
Acute endocarditis unspecified
  • Short description: AC/SUBAC ENDOCARDIT NOS.
  • ICD-9-CM 421.9 is a billable medical code that can be used to indicate a diagnosis on a reimbursement claim, however, 421.9 should only be used for claims with a date of service on or before September 30, 2015. For claims with a date of service on or after October 1, 2015, use an equivalent ICD-10-CM code (or codes).
  • You are viewing the 2006 version of ICD-9-CM 421.9.
  • More recent version(s) of ICD-9-CM 421.9: 2007 2008 2009 2010 2011 2012 2013 2014 2015.
Convert to ICD-10-CM: 421.9 converts directly to:
  • 2015/16 ICD-10-CM I33.9 Acute and subacute endocarditis, unspecified
Approximate Synonyms
  • Acute endocarditis
  • Acute endocarditis (infection of heart valve)
  • Acute nonbacterial endocarditis
  • Endocarditis (infection of heart valve), subacute
  • Endocarditis, acute
  • Endocarditis, nonbacterial, acute
  • Endocarditis, subacute
  • Subacute endocarditis
  • Subacute endocarditis (infection of heart valve)
421.9 Excludes
  • acute rheumatic endocarditis (391.1)
Applies To
  • Endocarditis, acute or subacute
  • Myoendocarditis, acute or subacute
  • Periendocarditis, acute or subacute
ICD-9-CM Volume 2 Index entries containing back-references to 421.9:
  • Endocarditis (chronic) (indeterminate) (interstitial) (marantis) (nonbacterial thrombotic) (residual) (sclerotic) (sclerous) (senile) (valvular) 424.90
    • acute or subacute 421.9
      • rheumatic (aortic) (mitral) (pulmonary) (tricuspid) 391.1
        • with chorea (acute) (rheumatic) (Sydenham's) 392.0
    • aortic (heart) (nonrheumatic) (valve) 424.1
      • with
        • mitral (valve) disease 396.9
          • active or acute 391.1
            • with chorea (acute) (rheumatic) (Sydenham's) 392.0
            • bacterial 421.0
        • rheumatic fever (conditions classifiable to 390)
          • active - see Endocarditis, acute, rheumatic
          • inactive or quiescent (with chorea) 395.9
            • with mitral disease 396.9
      • acute or subacute 421.9
      • arteriosclerotic 424.1
      • congenital 746.89
      • hypertensive 424.1
      • rheumatic (chronic) (inactive) 395.9
        • with mitral (valve) disease 396.9
          • active or acute 391.1
            • with chorea (acute) (rheumatic) (Sydenham's) 392.0
        • active or acute 391.1
          • with chorea (acute) (rheumatic) (Sydenham's) 392.0
      • specified cause, except rheumatic 424.1
      • syphilitic 093.22
    • mitral (chronic) (double) (fibroid) (heart) (inactive) (valve) (with chorea) 394.9
      • with
        • aortic (valve) disease 396.9
          • active or acute 391.1
            • with chorea (acute) (rheumatic) (Sydenham's) 392.0
        • rheumatic fever (conditions classifiable to 390)
          • active - see Endocarditis, acute, rheumatic
          • inactive or quiescent (with chorea) 394.9
            • with aortic valve disease 396.9
      • active or acute 391.1
        • with chorea (acute) (rheumatic) (Sydenham's) 392.0
        • bacterial 421.0
      • arteriosclerotic 424.0
      • congenital 746.89
      • hypertensive 424.0
      • nonrheumatic 424.0
        • acute or subacute 421.9
      • syphilitic 093.21
    • pulmonary (chronic) (heart) (valve) 424.3
      • with
        • rheumatic fever (conditions classifiable to 390)
          • active - see Endocarditis, acute, rheumatic
          • inactive or quiescent (with chorea) 397.1
      • acute or subacute 421.9
        • rheumatic 391.1
          • with chorea (acute) (rheumatic) (Sydenham's) 392.0
      • arteriosclerotic or due to arteriosclerosis 424.3
      • congenital 746.09
      • hypertensive or due to hypertension (benign) 424.3
      • rheumatic (chronic) (inactive) (with chorea) 397.1
        • active or acute 391.1
          • with chorea (acute) (rheumatic) (Sydenham's) 392.0
      • syphilitic 093.24
    • toxic (see also Endocarditis, acute) 421.9
    • tricuspid (chronic) (heart) (inactive) (rheumatic) (valve) (with chorea) 397.0
      • with
        • rheumatic fever (conditions classifiable to 390)
          • active - see Endocarditis, acute, rheumatic
          • inactive or quiescent (with chorea) 397.0
      • active or acute 391.1
        • with chorea (acute) (rheumatic) (Sydenham's) 392.0
      • arteriosclerotic 424.2
      • congenital 746.89
      • hypertensive 424.2
      • nonrheumatic 424.2
        • acute or subacute 421.9
      • specified cause, except rheumatic 424.2
      • syphilitic 093.23
  • Myoendocarditis - see also Endocarditis
    • acute or subacute 421.9
  • Periendocarditis (see also Endocarditis) 424.90
    • acute or subacute 421.9
 421.1 ICD9Data.com 422 
ICD-9-CM codes are used in medical billing and coding to describe diseases, injuries, symptoms and conditions. ICD-9-CM 421.9 is one of thousands of ICD-9-CM codes used in healthcare. Although ICD-9-CM and CPT codes are largely numeric, they differ in that CPT codes describe medical procedures and services. Can't find a code? Start at the root of ICD-9-CM, check the 2006 ICD-9-CM Index or use the search engine at the top of this page to lookup any code.
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