Ask Dr. Z

Question: A 74-year-old patient with history of coronary artery disease (CAD), who is status post coronary artery bypass graft (CABG), presented to the emergency room with complaints of increasing chest pain over the last three days. The patient described intermittent chest pain lasting for approximately 20 minutes that started as back pain and bilateral shoulder pain, then radiated to the center of the chest. A proximal stenosis of the vein graft to the obtuse marginal branches with extensive thrombus was seen in the distal graft, which was likely the culprit lesion causing a non-ST elevation myocardial infarction (NSTEMI). It was noted that the patient also had severe native multi-vessel disease, and the other vein grafts appeared to be patent. In this case, is it appropriate to assign a code for CAD with angina for the severe native multi-vessel disease that resulted in the MI?

The answer is to code I21.4 as principal with I25.10 as additional. Why wouldn't you code I25.810 instead for the stenosis of the vein graft? Should I code both I25.10 and I25.810?