Coding corner

How to code coronary artery disease (CAD): 414.00 vs. 414.01

There is a sneaky little ICD-9-CM coding rule that coders sometimes don't know about, and so coders occasionally code diagnoses incorrectly. The issue involves coronary artery disease (CAD).

Coronary artery disease, with no other information available to indicate that the patient has some non-native coronary vessels or grafts in place, is properly coded as 414.01 Coronary Athersclerosis of Native Coronary Artery. It is often thought erroneously by coders that 414.00 is used when the type of diseased artery is not specified.

Actually, coders can only report code 414.00 Coronary Athersclerosis of Unspecified Type of Vessel, Native or Graft if the documentation indicates that the patient does have non-native coronary vessels from a coronary artery bypass graft (CABG) and that the physician didn't specify where the CAD is in the patient. To many coders, this may seem backward or counterintuitive. Coders often think that if the physician did not specify which type of artery has the coronary artery disease, then the unspecified 414.00 code should automatically be reported. That is not the case. 

Two criteria must be met: coders can only report the 414.00 code if the physician didn't document which type of artery has the disease and if there is documentation present that indicates that the patient actually has both native and non-native coronary arteries.

To clarify, without the necessary supporting documentation, coders are not allowed to assume that the patient has any non-native coronary arteries (grafts) in the first place. Unless there is documentation that there are such non-native (graft) coronary arteries, there is never any need for the physician to specify which kind of artery (native or graft) has the CAD. Coders must, according to proper ICD-9-CM coding instructions, presume any unspecified arteries with CAD to be native arteries unless the patient actually has both kinds of arteries documented. Only then can coders use the unspecified code if the physician didn't specify which type of artery has the CAD.

Here's the official coding rule from the second quarter, 1995 issue of Coding Clinic for ICD-9-CM:

Question: Is it appropriate to assign code 414.01, Coronary atherosclerosis, of native coronary artery, if the medical record documentation does not indicate that the patient has a history of prior coronary artery bypass surgery?

Answer: Assign code 414.01, Coronary atherosclerosis, of native coronary artery, if medical record documentation shows no history of prior coronary artery bypass.  If the documentation is unclear concerning prior bypass surgery, query the physician.

Because so many coders overlooked the rule the first time it was officially published in 1995, the official coding rule was reiterated in the third quarter, 1997 issue of Coding Clinic for ICD-9-CM:

Question: A patient has coronary artery disease. There is no mention of a past history of CABG. Should this be coded to 414.00, Coronary atherosclerosis of unspecified type of vessel, native or graft, or 414.01, Coronary atherosclerosis of native coronary artery?

Answer: Assign code 414.01, Coronary atherosclerosis of native coronary artery. Since there is no history of CABG, this is a native coronary vessel. However, if the documentation is unclear concerning prior bypass surgery, query the physician. This is consistent with advice previously published in Coding Clinic, second quarter 1995, page 17.

So, the coding rule is that in order to use the 414.00 "unspecified type of graft" code, coders need to know that the patient does have a graft and that the physician didn't specify where the CAD was, in the patient's native artery or in the patient's graft. Without any indication that the patient has a graft, the type of CAD doesn't need to be specified from an ICD-9-CM coding standpoint, it's presumed to be native if there's no evidence of a graft; coders must use 414.01.

This coding rule is indeed counterintuitive in many ways and even Coding Clinic for ICD-9-CM is not immune from getting things mixed up a bit. In the fourth quarter 2003 issue of Coding Clinic for ICD-9-CM, coders were instructed mistakenly to report code 414.01 in a patient who had both CAD and a previous history of coronary artery bypass grafting. Coders who saw this commentary without also seeing the later correction probably thought that Coding Clinic for ICD-9-CM had changed its coding policy. They actually didn't. Coding Clinic for ICD-9-CM issued an official correction two issues later, in the first quarter 2004 issue:

"Coding Clinic, fourth quarter 2003, page 106, advised code 414.01, Coronary atherosclerosis, Of native coronary artery, for a patient with a history of CAD status post coronary artery bypass graft (CABG). However, code 414.00, Coronary atherosclerosis, Of unspecified type of vessel native or graft, is the appropriate code assignment. According to Coding Clinic, second quarter 1995, page 17, and third quarter 1997, page 15, code 414.01 is assigned when the medical record documentation does not indicate that the patient has a history of prior coronary artery bypass surgery or the physician has documented the presence of atherosclerosis in a native coronary artery."

Gregory Schnitzer, CodeRyte, Inc.

Revised Jan. 23, 2007