I25.700

Atherosclerosis of coronary artery bypass graft(s), unspecified, with unstable angina pectoris

Atherosclerosis of coronary artery bypass grafts (CABG) is a progressive condition where the grafts used in a previous revascularization surgery—whether venous or arterial—develop atherosclerotic plaques. When this narrowing causes unstable angina pectoris, it represents a form of acute coronary syndrome (ACS) where the clinical symptoms are unpredictable, occurring at rest or with minimal exertion, and are significantly more severe or frequent than previously experienced. The 'unspecified' classification denotes that the specific type of bypass graft (e.g., autologous vein vs. internal mammary artery) is not identified in the clinical documentation. This condition is a serious complication of coronary artery bypass surgery and requires urgent medical evaluation, as it indicates a high risk for complete graft occlusion and subsequent myocardial infarction. Management often involves aggressive medical therapy and potentially repeat revascularization through percutaneous coronary intervention or redo-CABG.

Clinical Symptoms

Crescendo angina (increasing frequency or intensity)
Chest pain occurring at rest
New-onset severe chest pain
Radiation of pain to the jaw, neck, or left arm
Dyspnea (shortness of breath)
Diaphoresis (profuse sweating)
Nausea and vomiting
Extreme fatigue
Palpitations
Lightheadedness or syncope

Common Causes

Chronic atherosclerosis within the bypass graft
Intimal hyperplasia (early stage graft failure)
Long-standing hypertension
Dyslipidemia with high LDL cholesterol
Diabetes mellitus
History of cigarette smoking
Sedentary lifestyle and obesity
Genetic predisposition to coronary artery disease
Chronic systemic inflammation

Documentation & Coding Tips

Clarify the graft type to move beyond the unspecified code.

Example: Patient with known coronary artery disease and status-post CABG in 2015 presents with crescendo chest pain. Review of operative reports identifies the affected vessel as an autologous saphenous vein graft to the RCA. Documentation of the specific graft material allows for transitioning from I25.700 to the more specific I25.710.

Billing Focus: Identify graft material such as autologous vein, autologous artery, or nonautologous biological material to ensure maximum specificity.

Define the nature of the unstable angina with clinical indicators.

Example: Patient reports chest pain occurring at rest that has increased in frequency and duration over the last 48 hours, previously stable on isosorbide mononitrate. The angina is now refractory to sublingual nitroglycerin. This documentation of crescendo pattern and rest pain supports the unstable angina component of I25.700.

Billing Focus: Document the pattern of symptoms, including rest pain or accelerating frequency, to justify the acute ischemic code.

Distinguish between native vessel disease and bypass graft disease.

Example: Cardiac catheterization reveals 90 percent stenosis in the 2019 vein graft to the LAD, while the native LAD remains chronically occluded. Clinical documentation specifies that the current unstable symptoms are attributable to the atherosclerosis of the coronary artery bypass graft rather than native vessel progression.

Billing Focus: Specify if the atherosclerosis is located in the native vessel (I25.110) or the graft (I25.700) to ensure accurate site coding.

Incorporate tobacco use or exposure history.

Example: Patient with atherosclerosis of coronary artery bypass graft and unstable angina pectoris continues to smoke one pack of cigarettes per day. Assessment: I25.700 with comorbid F17.210 (Nicotine dependence, cigarettes, with pathology).

Billing Focus: Associated nicotine dependence codes should be sequenced as secondary diagnoses to reflect underlying contributors to atherosclerosis.

Link the atherosclerosis to the current angina episode.

Example: Diagnosis: Atherosclerosis of coronary artery bypass graft with unstable angina pectoris. The patient is exhibiting new-onset ischemia during minimal exertion, directly linked to progressive graft stenosis confirmed via imaging. No evidence of NSTEMI at this time (troponin negative).

Billing Focus: Explicitly state the causal relationship between the graft atherosclerosis and the unstable angina to satisfy the 'with' convention in ICD-10-CM.

Document previous CABG details for context.

Example: The patient underwent triple coronary artery bypass graft surgery 12 years ago. Current presentation of unstable angina is associated with suspected atherosclerosis of these grafts. The long-term status of the grafts is a primary focus of the current diagnostic workup.

Billing Focus: Use Z95.1 (Presence of aortocoronary bypass graft) as a supplemental code to confirm the patient surgical history if not part of the primary code description.

Relevant CPT Codes

99215 - Office or other outpatient visit for the evaluation and management of an established patient, which requires a high level of medical decision making
Unstable angina in a post-CABG patient typically involves high complexity due to the risk of imminent MI and multiple treatment options.
99205 - Office or other outpatient visit for the evaluation and management of a new patient, which requires a high level of medical decision making
New patients presenting with graft failure and unstable symptoms require intensive evaluation and planning.
99214 - Office or other outpatient visit for the evaluation and management of an established patient, which requires a moderate level of medical decision making
Used for monitoring symptoms that are currently stabilized but require close follow-up.
93454 - Catheter placement in coronary artery(s) for selective coronary angiography
Essential for identifying the specific location and severity of graft atherosclerosis causing unstable symptoms.
93458 - Catheter placement in coronary artery(s) for selective coronary angiography with left heart catheterization
Standard procedure for evaluating hemodynamics and anatomy in unstable angina patients.
92928 - Percutaneous transcatheter coronary stent placement, single major coronary artery or branch
Common treatment for focal atherosclerosis within a bypass graft to resolve unstable angina.
93000 - Electrocardiogram, routine ECG with at least 12 leads
Initial diagnostic step to check for ST-segment changes or T-wave abnormalities.
93306 - Echocardiography, transthoracic, real-time with image documentation (2D)
Used to assess wall motion abnormalities that may result from graft ischemia.
33533 - Coronary artery bypass, using arterial graft(s); single arterial graft
If the existing graft has failed due to atherosclerosis, a re-operation (RE-DO CABG) may be performed.
99233 - Subsequent hospital care, per day, for the evaluation and management of a patient, which requires a high level of medical decision making
Management of a hospitalized patient with unstable symptoms following a graft failure.
99291 - Critical care, evaluation and management of the critically ill or critically injured patient; first 30-74 minutes
Applied if the unstable angina leads to cardiogenic shock or life-threatening arrhythmias.
99213 - Office or other outpatient visit for the evaluation and management of an established patient, which requires a Low Complexity MDM or 20-29 Minutes of medical decision making
Used for routine follow-up of a patient with bypass grafts who is currently asymptomatic.