The Current Procedural Terminology (CPT) system provides a standardized language for reporting medical services and procedures. CPT code 75574 identifies a comprehensive computed tomography (CT) scan of the heart, detailing the coronary arteries and critical blood vessels. This advanced cardiac imaging procedure is central to the diagnosis and management of coronary artery disease. Understanding its technical components, clinical applications, and strict documentation requirements is essential.
Defining the Computed Tomography Procedure
CPT code 75574 describes a Coronary Computed Tomographic Angiography (CCTA) of the heart, including the coronary arteries and any bypass grafts. This non-invasive imaging test uses high-speed CT technology combined with an intravenous injection of iodinated contrast material. The procedure captures detailed, three-dimensional images of the coronary vasculature, allowing physicians to visualize the arteries from multiple angles.
The technical steps begin with continuous monitoring of the patient’s heart rhythm using an electrocardiogram (ECG). This ECG gating synchronizes the CT scanner’s image acquisition with the heart’s resting phase, minimizing motion blur. A non-contrast scan is often performed first to measure calcified plaque, followed by the rapid injection of contrast dye.
Once the contrast fills the coronary arteries, the high-speed CT scanner acquires images in seconds. The contrast makes the blood flow and the inner lining of the arteries visible, enabling the detection of narrowings or blockages. Extensive computer post-processing generates high-resolution, three-dimensional reconstructions of the heart and its vessels for detailed analysis.
Clinical Application for Cardiac Assessment
This comprehensive cardiac assessment is ordered for patients with symptoms suggestive of coronary artery disease (CAD) who have an intermediate pre-test probability of the condition. For example, a patient with atypical chest pain or unexplained shortness of breath who lacks a definitive diagnosis from simpler tests may be referred. The high negative predictive value of CCTA is a primary clinical strength, as a negative result reliably rules out significant obstructive CAD.
The procedure also evaluates known or suspected coronary artery anomalies and assesses the patency of coronary artery bypass grafts in post-surgery patients. The resulting images provide a detailed anatomical map, allowing for the quantification of plaque burden and the identification of significant stenosis, or narrowing, in the coronary arteries. This information is used to stratify the patient’s risk and guide subsequent treatment decisions, such as starting aggressive medical therapy or proceeding with an invasive angiogram.
Mandatory Elements for Billing Compliance
The official CPT description for 75574 mandates the use of contrast material and 3D image post-processing for the coronary arteries. The physician’s report must document the detailed reconstruction and interpretation of the coronary tree and any bypass grafts. Beyond the technical components, documentation must also confirm the evaluation of cardiac structure, morphology, and function, justifying the code’s complexity compared to simpler CT heart codes.
For many payers, the service must be supported by extensive documentation of derived quantitative measurements. The physician’s report must clearly articulate the findings from the sophisticated 3D models and provide quantitative measurements, often including metrics related to the coronary calcium score. Adherence to these strict documentation rules ensures the reported service accurately reflects the complex technical and professional work involved in interpreting the advanced imaging.
Interpreting the Calcium Scoring and Measurements
The initial non-contrast portion of the scan provides the Coronary Artery Calcium (CAC) score, calculated using the validated Agatston method. This score quantifies the total amount of calcified atherosclerotic plaque, serving as a powerful indicator of a patient’s total plaque burden. A CAC score of zero suggests a very low risk of a near-term cardiac event, while a score of 400 or higher is associated with a high burden of atherosclerotic disease.
The quantitative measurements from the contrast-enhanced scan determine the severity of blockages. Stenosis is quantified by measuring the percentage reduction in the vessel’s diameter at the plaque site compared to a healthy segment. This quantification allows the care team to distinguish between non-flow-limiting plaque and significant coronary artery narrowing, often defined as a reduction of 50% or more. Integrating the Agatston score with the stenosis measurements provides a comprehensive picture of the presence and functional impact of coronary artery disease.