Knowing the cause of cardiomyopathy lead to correct ICD-9-CM code

Editor’s note: This tip originally appeared in “Briefings on APCs.”

Specific ICD-9-CM codes in the 425 code series exist for each type of cardiomyopathy. For example, codes 425.11 and 425.18 denote idiopathic hypertrophic cardiomyopathy with or without obstruction, respectively. Code 425.5 denotes alcoholic cardiomyopathy. Code 425.7 denotes nutritional cardiomyopathies, such as due to amyloidosis and beriberi. Some very rare cardiomyopathies are also specifically named in this section. Two examples are endocardial fibroelastosis (code 425.3) and obscure cardiomyopathy of Africa (code 425.2).

Code 425.8 denotes other specified cardiomyopathies in diseases classified elsewhere that can also affect the heart muscle and its function. These include Friedreich’s ataxia, progressive muscular dystrophy, sarcoidosis, and myotonia atrophica.

Other specific causes of cardiomyopathy are not included in the 425 code series.

If you look for hypertensive cardiomyopathy in the Alphabetic Index of the ICD-9-CM Manual, it leads you to hypertension with cardiac involvement. This leads you to the 402–404 code series. Hypertensive cardiomyopathy is a type of cardiomyopathy; however, it doesn’t exist in the 425 code series. Coding Clinic, Second Quarter 1993, p. 9, instructs coders to assign both the 402 (or 404) series code and code 425.8 to designate cardiomyopathy in diseases classified elsewhere.

Similarly, ischemic cardiomyopathy (code 414.8) is not listed under cardiomyopathy even though it is a cause of heart disease that can lead to dysfunction. No advice exists for the addition of code 425.8 even though it is among the most frequent causes of cardiomyopathy in the United States. This represents an error in the coding system. ICD-9-CM code 414.8 denotes ischemic heart disease just as codes 403 and 404 denote hypertensive heart disease. They each require code 425.8 to capture the complete description of the condition.