Cardiology Coding Alert

Question: When the cardiologist places a stent in a coronary bypass graft, which modifier should we use? For example, if the patient has a saphenous vein graft going from the aorta to the right coronary artery, should we use a modifier to identify the graft?

Indiana Subscriber

Answer: Typical payer policies will instruct you to append modifier RC (Right coronary artery) for the case you describe.

Here's why: When the cardiologist places a stent in a coronary graft, you should use an anatomic modifier just as you would if she placed the stent in a native coronary vessel. For many payers, you will find written policies instructing you to base the modifier you use for the graft on the vessel the blood flows into.

Modifiers: The modifiers in question are RC, LC (Left circumflex coronary artery), and LD (Left anterior descending coronary artery).

In your example, the graft attaches to the aorta and the right coronary artery, allowing blood to flow into the right coronary artery. Therefore, when reporting stent placement in this graft, you should append modifier RC. For instance, you may append RC to 92980 (Transcatheter placement of an intracoronary stent[s], percutaneous, with or without other therapeutic intervention, any method; single vessel).

National Government Services (NGS), Part B carrier for Indiana, supports this modifier use in its "Local Coverage Article for Percutaneous Coronary Interventions -- Supplemental Instructions Article (A50611)." The article states that "Medicare recognizes only three coronary arteries when considering first and additional vessel interventions: the left anterior descending, the left circumflex and the right coronary arteries ... Bypass conduits are considered to be integral to the vessel of distal anastomosis."

If you don't append an artery modifier, NGS will return the claim as not processable, the article warns.

More on grafts: Coronary bypass grafts allow blood to "bypass" an area of obstruction in a coronary artery. Often, bypass grafts are proximally connected to the aortic arch and distally connected to a diseased coronary artery downstream from the obstruction. This bypass vessel provides blood flow to the heart muscle (myocardium) that has been deprived of blood flow due to the obstruction.

Saphenous and radial grafts, harvested from elsewhere in the body, are attached proximally and distally to create the bypass. However, left internal mammary artery (LIMA) and right internal mammary artery (RIMA) grafts are only attached distally. These two artery grafts are known as live grafts because one end of the graft is left attached to the native vessel.