Coding mitral valve disease

November 15th, 2019 / By Rebecca Caux-Harry

Last month, I wrote about accurate coding for aortic valve disease. This month, we’ll look at coding for mitral valve disease. The mitral valve is located in the left side of the heart between the atrium and ventricle. This valve is generally considered the second most important valve, secondary to the aortic valve. When the left atrium contracts, the mitral valve opens allowing the contents to be pushed into the left ventricle. Contraction of the left ventricle causes the mitral valve to close, preventing backward flow of blood into the left atrium. A normal healthy mitral valve has two leaflets that when closed, meet together closing the opening between the two heart chambers.

When the two leaflets overlap, this is called mitral valve prolapse. This is a lifelong disorder, but patients rarely have symptoms and the condition rarely impacts the patient. This is an easy one. There is only one code, I34.1 Nonrheumatic mitral (valve) prolapse.

Mitral valve prolapse can sometimes lead to blood leaking back through the valve leaflets into the left atrium. This condition is now called mitral valve insufficiency or regurgitation. Additionally, mitral insufficiency can occur without prolapse. Stenosis of the mitral valve is a narrowing of the valve opening, which restricts blood flow through the valve. Prolapse, insufficiency and stenosis can occur separately or in combination with each other.

When looking in the ICD-10 index under disease, Mitral (valve), we are given two options:

I05.9 Rheumatic mitral valve disease, unspecified and

I34.9 Nonrheumatic mitral valve disorder, unspecified.

Don’t be misled by this. Disease can mean many things.  Keep digging. From this notation, should we assume that mitral valve disease is rheumatic unless otherwise stated? Maybe. The Includes note associated with I05 states “conditions classifiable to both I05.0 and I05.2-I05.9, whether specified as rheumatic or not.” 

Coding for mitral valve disease requires clear documentation of the type and origin of the disease. If the disease is specified as rheumatic, we have the following codes:

I05.0      Rheumatic mitral stenosis

I05.1      Rheumatic mitral insufficiency

I05.2      Rheumatic mitral stenosis with insufficiency

I05.8      Other rheumatic mitral valve diseases

I05.9      Rheumatic mitral valve disease, unspecified

Remember from last month’s blog that disease in multiple valves is assumed to be rheumatic.  Those codes can be found in I08.

When the physician documents the disease is nonrheumatic, we have the following codes:

I34.0      Nonrheumatic mitral (valve) insufficiency

I34.1      Nonrheumatic mitral (valve) prolapse

I34.2      Nonrheumatic mitral (valve) stenosis

I34.8      Other nonrheumatic mitral valve disorders

I34.9      Nonrheumatic mitral valve disorder, unspecified

If the patient’s mitral valve disease is specified as congenital, we use the following codes:

Q23.1    Congenital mitral stenosis

Q23.3    Congenital mitral insufficiency

Q23.8    Other congenital malformations of aortic and mitral valves

Q23.9    Congenital malformation of aortic and mitral valves, unspecified

Congenital valve disease can also be included in other more severe cardiac defects, so carefully review the physician’s documentation to insure you are coding to the highest degree of specificity.  We have several things to keep in mind when looking for the correct ICD-10 code, including the type of disease (stenosis, insufficiency or regurgitation, prolapse), origin of disease (congenital, or not) and cause (rheumatic or not).  Make sure to read the tabular section, the full descriptors and the Includes/Excludes notes in order to select the correct code.

Rebecca Caux-Harry, CPC, is a professional fee coding specialist with 3M Health Information Systems.