The American Medical Association notes that infusion-and-hydration codes are among the most error-prone for coders; start/stop times, therapeutic vs. hydration classification, and documentation are often the reasons to blame. 

This guide explains the correct use of procedure code 96365, including its definition, applicable clinical scenarios, required modifiers, and billing documentation rules to ensure compliance with CMS 2025 standards.

CPT Code 96365 Description

CPT code 96365 is the procedural code that is used to report the initial intravenous infusion of a therapeutic, prophylactic, or diagnostic substance or drug. AMA CPT 2026 defines that CPT code 96365 represents the first hour of IV infusion provided under the guidance of a qualified healthcare professional.

In practice, code 96365 defines the administration of a solution or medications into a patient’s vein during a continuous period, including up to sixty (60) minutes. Medications or solutions may include therapeutic infusions (ex., IV antibiotics), prophylactic infusions (e.g., preventative medications), and diagnostic infusions (e.g., contrast used in a test).

However, this code does not include chemotherapy or biologic infusions. These are, however, billed under specialized codes such as CPT 96413. Within drug administration coding, CPT 96365 serves as a foundational code for infusion therapy. It ensures proper billing for the skill, time, and supervision required to perform and monitor the IV infusion. 

Accurate use of this code also supports compliance with CMS and payer documentation requirements for infusion therapy.

Clinical Scenarios Where CPT Code 96365 is Applicable

A clear understanding of the real-world applications of CPT code 96365 helps to make sure that the code is correctly used. Below are common therapeutic IV infusion coding examples that meet medical necessity and documentation criteria.

Micronutrient IV Infusion for Treating Vitamin Deficiencies

In a clinical environment, a patient might be infused with micronutrient therapeutic IV infusion to treat vitamin deficiencies. The supervision of the infusion is billed using CPT 96365. This is mainly because it signifies an initial intravenous infusion for a duration of one hour or less.

To guarantee the application of the code in compliance, providers must document:

• Exact beginning and end time of the infusion
• Names and dosages of administered agent(s)
• Details on patient monitoring and physician supervision

Prophylactic Antibiotic Infusion Before Surgery

A prophylactic infusion that is monitored before a procedure to prevent infection is also considered for CPT 96365. When performed on the same day of service as an E/M visit, documentation should establish the requisite linkage between the infusion and the E/M visit.

According to CMS billing rules, infusions and E/M services may both be billable when medically necessary, and it is clearly documented. This example demonstrates the importance of medical necessity documentation and payer compliance.

Applicable CPT 96365 Modifiers 

Modifiers ensure precise claim processing and help communicate that multiple procedures or infusions were distinct or separately identifiable. For CPT code 96365, only the modifiers are used that are consistent with the CMS infusion administration rules 2025 and the NCCI edits guide. 

Modifier 59 and Subcategory Modifiers X{EPSU}

• Modifier 59 for CPT 96365– This modifier is used when the IV infusion is discrete and separate from other services that are performed on the same day.
• XE (Separate Encounter) – This modifier is used when an Infusion is performed during a different patient encounter. 
• XP (Separate Provider) – In using this modifier, the infusion is administered by a different clinician.
• XS (Separate Site) – When an Infusion is performed at a different anatomical site or vascular access point, the XS modifier is used. 
• XU (Unusual Non-Overlapping Service) – This modifier applies when an Infusion does not overlap with other service components.

Proper use of these modifiers allows billing systems to bypass NCCI bundling edits, but incorrect or excessive use can trigger payer audits, denials, or compliance reviews.

How to Bill CPT Code 96365: Reimbursement and Compliance Guidelines

Do you want to boost your collection for intravenous infusions? Below are the essential IV infusion billing guidelines every provider and coder should follow.

CPT 96365 Documentation Requirements

Taking accurate notes of the infusion start and stop time is essential. The reported duration determines if CPT 96365 (initial hour) or CPT 96366 (each additional hour) is applied to the situation.
Incomplete or estimated times can lead to claim rejections under CMS infusion administration rules 2025.

Reporting Subsequent Infusions Beyond the Initial Hour 

CPT code 96365 should only be billed once per encounter for the initial hour.
For infusions extending beyond that first hour, report:

• CPT 96366 – For each additional hour of the same drug.
• CPT 96367 – For sequential infusion of a new drug or substance.

This approach ensures accurate reporting of sequential infusion CPT coding and compliance with payer time-based billing rules.

Coding Concurrent Infusions Correctly 

When multiple drugs are infused at the same time through separate IV lines, it’s considered a concurrent infusion.
Instead of 96365, CPT code 96368 is to report concurrent administration.
This difference between the codes prevents double-billing and maintains compliance with infusion administration guidelines.

Establishing Medical Necessity Through Complete Documentation 

To meet payer criteria for CPT 96365 medical necessity, documentation should include:

• The symptoms a patient has and the resulting diagnosis
• Date of service and exact start/stop times
• Medications used, dosage, and the route of infusion 
• Adverse reactions or monitoring details

Strong infusion therapy documentation supports compliance and successful CPT 96365 billing and reimbursement.

Pairing CPT 96365 with the Appropriate HCPCS Drug Code 

CPT 96365 covers only the administration of the infusion—not the medication itself.
To bill the drug separately, pair it with the appropriate HCPCS J-code that identifies the infused substance.

Example:

• J0690 – Cefazolin injection, per 500 mg (for prophylactic antibiotic infusion).

Using the correct HCPCS code 96365 pairing ensures that both the infusion and the drug are reimbursed appropriately under Medicare billing for infusion therapy.

Can We Bill CPT Codes 96365 and 96413 Together?

CPT 96365 and CPT 96413 reflect different infusion administrations: therapeutic/prophylactic and chemotherapy. They can only ever be reported together if each infusion is performed at a different anatomical site or different evaluation and management encounter. 

As an example, if a patient were to have a therapeutic infusion through one IV line and a chemotherapy infusion through a different IV, then the coder could report both codes.

Modifier 59 would be added to indicate distinct procedural services, regardless of NCCI edits for infusion coding. Proper documentation to include the site of infusion, time, and medical determination for infusion provides an appropriate defensive audit for payer acceptance.

Summary and Key Takeaways

Using CPT Code 96365 involves correctly recording all the details involved in the administration of an intravenous infusion of a medication or other substance for the initial hour. 

Below is a brief reminder:

covers the administration of. Second, we shared some clinical scenarios where this code can be reported for billing accuracy. 

• CPT 96365 indicates the first hour of a therapeutic, prophylactic, or diagnostic intravenous (IV) infusion
• For additional IV intravenous infusions, the appropriate codes CPT 96366 – 96368 should be used for administration that follows sequentially or concurrently to the initial service 
• Modifiers, including 59, XE, XP, XS, XU, should only be properly applied and addressed when coded under National Correct Coding Initiative edits and CMS 2025 rules
• Assist the duration of the infusion and medical necessity should also be documented
• A HCPCS code to support the drug used in conjunction with infusion.

You can let the experts manage complex infusion coding, documentation, and payer compliance for you. Outsource your internal medicine billing to Nexus IO. 

FAQs on CPT Code 96365

What is the difference between CPT codes 96365 and 96374?

Both these codes involve intravenous drug administration. However, both are used for different purposes:

• CPT 96365 – It is used for Initial intravenous infusion, up to one hour.
• CPT 96374 – This CPT code is used for the initial intravenous push of a therapeutic, prophylactic, or diagnostic substance.
• CPT 96375 – Each additional IV push of a new drug or substance.
  Even small distinctions between these codes significantly impact billing accuracy and compliance.

Is CPT 96365 covered by Medicare?

Yes. However, when performed on the same day as an Evaluation and Management (E/M) service (e.g., CPT 99221), CPT 96365 is typically bundled into the E/M code under the Medicare Physician Fee Schedule (MPFS). In such cases, the infusion code is not separately payable unless properly justified with documentation and modifiers.

Can CPT 96365 be reported in an observation or inpatient setting?

Yes. CPT 96365 can be billed in both outpatient and inpatient settings, provided the service is performed by a qualified professional and separately documented. The code must represent direct supervision when applicable, as defined by Medicare hospital outpatient billing guidelines.

Can CPT 96365 be used for hydration therapy?

No. CPT 96365 must not be used for hydration services. Hydration infusions are reported separately using CPT 96360 (initial hour of hydration infusion) and CPT 96361 (each additional hour). Reporting hydration under CPT 96365 is noncompliant with NCCI edits and may result in claim denials.

Each five-digit CPT code in medical billing and coding has more value and significance than you might realize. These codes are the mechanism through which healthcare providers articulate the value of their clinical services to their payers. Their specificity and accuracy of use determine if a claim gets reimbursed in a timely fashion or results in another unpaid item on the ledger.  

Among thousands of CPT codes defining today’s healthcare, CPT code 99213 is one of the most utilized. In the following, let’s break down CPT 99213 together, so that every minute of care you provide gets converted into efficient and accurate reimbursement.

Description of CPT Code 99213

CPT Code 99213 defines a Level 3 office or outpatient visit for an established patient. According to the American Medical Association (AMA), procedure code 99213 is used when a healthcare provider, for example, a primary care physician, orthopedist, or clinical psychologist, spends 20 to 29 minutes on the date of the encounter, or the visit involves low-complexity medical decision-making (MDM).

Concepts to Understand Before Using CPT 99213

Evaluation and Management (E/M) Visits

E/M codes capture cognitive services provided by either a physician or a qualified healthcare practitioner. CPT code 99213 specifically captures established patients with low complexity Medical Decision Making (MDM) or 20-29 minutes of total time. Each element, history, exam, and MDM, must correspond to the visit type and complexity.

Low-Complexity Medical Decision Making

Low-complexity MDM is appropriate for conditions involving limited information or data review, minimal risk, and simple clinical decision making. Examples would include the management of stable chronic disease (hypertension, diabetes) or an acute, uncomplicated issue.

For CPT 99213:

• Problems: One or more stable chronic illnesses or an acute, uncomplicated problem.
• Data: Limited data review (labs, notes, or imaging)
• Risk: Low level of complication or morbidity

Established Patients in an Outpatient Setting

The 99213 procedure code applies only to established patients, those who have been seen by the same provider or group (same specialty) within the past three years. It cannot be billed for new patients. Encounters usually take place in an office or outpatient clinic, but can also apply to telehealth visits when billed with Modifier 95 and the appropriate place of service (POS 02 or 10).

Scenarios Where CPT Code 99213 Is Applicable

These are some common types you may encounter in practice:

1. Follow-up of a Chronic Condition that is Controlled

A patient with hypertension returns for a follow-up for their blood pressure. The provider reviews the patient’s blood pressure logs. The provider then performs a focused exam and makes medication changes as appropriate. Overall, this encounter is of low complexity and may be billed using CPT 99213.

2. Routine Diabetes Follow-up or Check-in 

A patient with type 2 diabetes has a quarterly follow-up or check-in. The provider reviews the patient’s HbA1C, discusses diet, and reviews medication compliance. Since the patient’s diabetes is stable and the medication changes were small, this visit can be billed with CPT 99213. 

3. Follow-Up of New Side Effects from Medication

A patient returns stating they have had new side effects from the antidepressants that they are taking. The provider performs a focused history and appropriate exam, makes small discussions about medication choice, and possibly a dosage change. This is both a simple evaluation and treatment plan (prescribing medication). This is an easy case to utilize CPT 99213.

4. Mild or Minor Acute Illness Visit

A patient presents to the clinic with a sore throat and low-grade fever. The provider performs an exam, potentially does a rapid strep test, and provides a low complexity treatment plan. The overall MDM is low complexity and a routine visit. Overall, this is a CPT 99213 visit.

5. Follow-Up Appointment for Injury

A patient with a healing fracture attends the follow-up appointment. The provider reviews the X-rays, assesses the patient’s mobility, and provides home exercise recommendations. Because the patient is making predictable progress, this use case supports 99213.

6. Follow-Up Appointment for Mental Health Status

A patient with anxiety or any other mental health disorder presents for a medication management appointment. The provider checks in on the patient’s symptoms and makes slight adjustments to the medication dosage. As the condition remains stable, this follows the use case for code 99213.

Reimbursement Criteria for CPT Code 99213 

To receive appropriate reimbursement for CPT 99213, you must comply with the documentation and coding guidelines set forth by the AMA and CMS.

• Complexity: The visit must be of low-level medical decision-making (MDM). Billing CPT 99213 for moderate or high complexity can result in an increase in the chances of over- or under-coding.
• Documentation: The notes must include a detailed history that is focused on the exam, and a low-complexity MDM that supports the need for the visit.
• Time: When billing based on the data of overall time spent on the date of service, include documentation of 20-29 minutes of the total time of the visit. 
• Place of Service (POS): POS 02 or POS 10 with Modifier 95 are used for telehealth visits. 
• Exclusive Billing Rule: CPT 99213 cannot be billed with another E/M code on the same day for the same patient. Only the higher-level service would be payable.
• Medical Necessity: The visit must be reasonable and necessary with documentation supporting the provider’s evaluation and management.

Common CPT 99213 Billing Errors Leading to Denied Claims

Maintaining strong Evaluation and Management documentation protects the provider during CMS audits and ensures timely payment. While CPT 99213 is frequently utilized, it is also frequently denied due to user errors. The common errors include the following: 

• Partial documentation: Missing details in the patient’s history, exam, or MDM.
• Incorrect E/M level: The complexity of this visit does not match the low-level MDM criteria of 99213. 
• Incorrect use of modifier: Modifier 25 was not used when another procedure or a service is billed on the same day. 
• Insufficient patient information: Lack of documentation for medication changes, diagnostic results, or care plans.
• Incorrect use of pos or telehealth coding: Use of an incorrect Place of Service or a missed required modifier will be reported for within the denial or for reduced payment.

Billing Guidelines for CPT Code 99213

When billing CPT 99213, regular internal audits and coder education on E/M documentation standards help keep compliance strong across all outpatient code 99213 encounters. 

Take note of the points below to ensure fewer denials: 

Patient Must Be Established

CPT 99213 is reserved for established patients being seen for the first time by you or your group in the past three years.

Level of Medical Decision-Making

Use 99213 when you have low-complexity MDM, usually seen with a stable chronic condition or uncomplicated acute problems. Use 99214 when the MDM requires complexity. 

Proper Documentation

You must include all required elements in your notes about the patient’s condition, notes from your physical examination, the treatment plan, and any rationale for your decisions. Clear and concise notes can assist with appropriate billing and potential compliance concerns. 

Time-Based Billing

When billing by time, you need to clearly document that the time was 20-29 minutes and what was done during the time, such as discussing tests or educating the patient.

Avoiding Coding Errors

Make sure that the E/M code you use is based on either the medical decision-making or time, so your practice does not lose revenue from under-coding or exposing your practice to being audited based on over-coding.

Payer and Compliance Rules

It is important to check for E/M documentation policies for each of your payors that can then be updated annually for the CMS.

 Correct Usage of Modifiers 25 and 95

Modifier 25 identifies that an E/M service, like procedure code 99213, was performed on the same day as another service but was significant and separately identifiable.
Modifier 95 indicates a synchronous telehealth E/M encounter, allowing providers to bill office visits delivered virtually. 

The Takeaway

While being one of the most E/M codes used, CPT code 99213 is prone to several misrepresentations. To master this code, it is imperative to maintain clear documentation of history, examination, and low-complexity decision-making. Ensuring strict adherence to payer and CMS standards is also another step you can take to minimize the denials for the CPT code. 

Many providers rely on professional billing partners like Nexus IO to provide medical billing services, ensuring each claim is fully documented, accurately coded according to CPT code 99213 billing guidelines, and processed without errors, leading to timely reimbursement and compliance peace of mind.

FAQs

What Is Low Complex MDM In CPT 99213?

CPT code 99213 involves making low-complexity medical decision making that groups a limited number of problems. It also involves gathering minimal data and taking care of low-risk issues.

What Is the Difference Between CPT 99213 and CPT 99214?

The basic difference between CPT 99213 and CPT 99214 relates to the time and complexity level of the services provided to the patient.

CPT 99213 implies low-complexity MDM (20-29 minutes) while CPT 99214 refers to moderate-complexity MDM (30-39 minutes).

 Is There a Specific Diagnosis Code for CPT 99213?

There is not a single diagnosis code (ICD-10-CM) associated with procedure code 99213. Rather, the diagnosis should represent the condition evaluated or managed at the visit accurately.

May a Nurse Practitioner or Physician Assistant Bill CPT 99213?

Yes. Qualified healthcare providers (QHPs) such as nurse practitioners (NPs) or physician assistants (PAs) may bill CPT 99213 if their documentation conforms to the same requirements as the Evaluation and Management (E/M) guidelines for physicians. The supervising physician’s NPI and the payers’ rules for shared or split visits must be followed.

How Does Time-Based Coding Work for CPT 99213?

For CPT 99213, its time-based coding applies if the provider spends 20–29 minutes on the date of service in satisfying all associated care, i.e., in both face-to-face and non-face-to-face activities within the visit.

Cardiology professionals and billing specialists are increasingly under pressure to capture every procedural detail as cardiovascular care grows in complexity. According to the American Heart Association (AHA), between 2020-2021, more than $417.9 billion was spent on cardiovascular disease in the U.S. This included direct medical costs and lost productivity. Error-free coding and billing for cardiology procedures is no longer just optional.

This blog provides a complete list of the top common cardiology CPT codes for 2026, with some billing guidelines, applicable modifiers, and some examples of ICD-10 pairings. Equipping clinicians, coders, and revenue cycle teams with the precision they need in cardiology billing and coding compliance.

Most Common Cardiology CPT Codes 2026 

Below are the most frequently used cardiology CPT® codes commonly used for both inpatient and outpatient cardiology services. Each description includes details on medical definition, average length of procedure, billing elements, applicable modifiers, ICD-10 code pairs, and reimbursement/compliance notes.

CPT Code 33945 – Heart Transplantation: 

Defined by the AMA, this code represents the complex heart transplantation procedure, including recipient cardiectomy and donor heart implantation. On average, it lasts 4–8+ hours, with ischemic times ideally under four hours. It’s a global surgical service covering the operation and immediate perioperative care. Under CMS reimbursement guidelines, facility and surgeon services must be billed separately. 

Only use modifier 22 if there is significant documentation and modifier 59 for unique or unusual circumstances. Typical ICD-10-CM linking: I50.22 (chronic systolic heart failure diagnosis). To remain within the compliance of HIPAA, it is important to maintain complete documentation of the transplant and ensure that a MAC or LCD has pre-authorized the case.

CPT Code 33935 – Donor Cardiectomy:

This CPT® code covers donor heart removal during multi-organ procurement. Timing varies based on donor availability and surgical coordination requirements. Facilities usually handle billing, while surgeons’ professional charges are managed under payer policies.

Modifier usage is expected to be consistent with institutional policy. Coding for the donor heart is – ICD-10-CM: Z52.4 (donor organ for heart), which can be used for all organ donors. Arranging billing per the Organ Procurement Organization (OPO) summary and CMS Medicare reimbursement systems/resources will support procedural accuracy related to billing and documentation details. 

CPT Code 33533 – Coronary Artery Bypass Graft (CABG) – Venous Grafts:

This code applies to CABG with a single venous graft. Average duration: 3–6 hours. It’s billed globally under CMS CPT® rules, including anesthesia. Combination modifiers use modifier 51 for multiple procedures, and modifier 22 for greater effort, as indicated by the NCCI rules and regulations. 

Coding for this procedure, ICD-10-CM is I25.10 (atherosclerotic heart disease). Documentation standards, especially around the procedure, include graft counts, operative notes, or drafts of the operative report to meet Medicare and Medicaid reimbursement guidelines.

CPT 93458 – Coronary Angiography:

This code is used for imaging supervision and interpretation during coronary angiography with left heart catheterization, as defined by the AMA CPT® manual. Average imaging time: 30–60 minutes. The physician bills the professional component with modifier 26, while the facility bills the technical component under HCPCS codes (Healthcare Common Procedure Coding System). ICD-10-CM pairing: I25.10. Always review CMS local coverage determinations (LCDs) and NCCI bundling rules.

CPT Code 92920 – Percutaneous Balloon Angioplasty:

This code includes percutaneous transluminal coronary angioplasty of one artery with a duration of time between 30 minutes and 3 hours. Please apply the NCCI edits when performing bundled procedures, and apply modifier 59 only when the service is a distinct procedural service. ICD-10-CM: I21.09 (STEMI). Proper coding and documentation in cardiology for payers is essential to prevent payer denials.

CPT Code 33206 – Permanent Pacemaker Insertion:

This code represents that the insertion of a permanent pacemaker with transvenous atrial leads typically takes 1–3 hours. Global period: 90 days. Covered under the Medicare physician fee schedule as a global service. Apply modifier 22 or 59 as needed, respecting E/M Services (Evaluation and Management) rules when same-day visits occur. ICD-10-CM: I49.5 (sick sinus syndrome). Comply with HIPAA and CMS billing rules for device implantation documentation.

CPT Code 93306 – Echocardiography:

This code indicates a full transthoracic echocardiogram with Doppler. Duration: 20–60 minutes. Bill the technical (modifier TC) and professional (modifier 26) components separately when appropriate. Add-on +93325 applies to color Doppler. ICD-10-CM: I35.0 or I50.1. Make sure that the cardiology documentation meets AMA and CMS diagnostic testing criteria for coverage.

CPT Code 93325 – Doppler Echocardiography:

This code is used as an add-on code for color flow velocity mapping during echocardiography; billed alongside 93306. No unique modifiers are required. ICD-10-CM: I42.0 (cardiomyopathy). Document Doppler use per CMS outpatient cardiology testing policy.

CPT Code 93224 – Holter Monitoring (24–48 Hours):

This code represents external ECG monitoring along with physician reading. Time frame: 24-48 hours. Add a modifier of 26. ICD-10-CM: R00.0 or R00.1. Assistance with the integration of outpatient cardiology or documentation if using CMS E/M coding guidelines, verifying the time frame criteria of the payer policy.

CPT Code 93015 – Cardiovascular Stress Test (Exercise):

This CPT code is used to report a complete cardiovascular stress test performed to assess the heart’s electrical and functional response to exercise or induced stress (such as treadmill, bicycle, or pharmacologic agents). The test is performed under ECG monitoring and supervision of a physician during the time-framed test. 

Time frame: 30-90 minutes. If coding for interpretation and reporting the procedure with testing service, add modifier 59. ICD-10-CM: R94.31 (abnormal ECG). If documentation includes any type of exercise testing, follow NCCI bundling criteria and CMS coverage.

CPT Code 93017 – Pharmacologic Stress Test:

This CPT code applies to cardiovascular stress testing performed with pharmacologic agents, in situations in which patients cannot participate in an exercise-based stress test because of a physical limitation or medical condition. 

With pharmacologic medications such as adenosine or regadenoson, practitioners can simulate the physiological effects of exercise while the myocardial blood flow and heart rate are increased. Time frame: 30-90 minutes. ICD-10-CM: I20.9. When coding an outpatient cardiology service, follow the guidelines of CMS for drug administration to patients.

CPT Code 93018 – Stress Test Interpretation & Report:

This CPT code is used to report the professional interpretation and formal report of cardiovascular stress tests. It represents only the professional component of the service and must be billed separately when the technical portion is performed by another entity. 

The corresponding modifier 26 should be appended to indicate interpretation-only billing. The ICD-10-CM code follows the primary diagnosis associated with the stress test, such as I20.9 (angina pectoris) or other ischemic conditions.

CPT Code 93010 – Electrocardiogram (ECG/EKG):

This CPT code is used to bill for the professional interpretation and report of a standard 12-lead electrocardiogram (ECG/EKG). It covers the physician’s diagnostic assessment, while facilities separately report CPT 93005 for the technical tracing component. The typical ICD-10-CM code is R00.0 (tachycardia) or another symptom-based cardiac diagnosis.

CPT Code 93000 – Electrocardiogram  ECG/EKG with Interpretation & Report:

This CPT code represents a complete 12-lead electrocardiogram service, including both the tracing and the physician’s interpretation with a signed report. The global service typically takes less than one hour to complete. The most common ICD-10-CM pairing is I48.91 (atrial fibrillation), though other arrhythmia or ischemic codes may apply.

When submitting claims, coders must comply with AMA CPT® professional-component billing standards and CMS technical–professional split guidelines to ensure proper revenue assignment and avoid duplication.

CPT Code 93005 – ECG/EKG, Tracing Only (Technical Component):

This CPT code is used to bill for the technical acquisition of the ECG tracing without interpretation. It applies to facilities or technicians who perform the test but do not provide a diagnostic report. The interpreting physician should separately bill CPT 93010 for the professional component. Claims should follow HCPCS and CMS technical-component billing rules.

CPT Code 93296 – ICD or Pacemaker Device Programming/Interrogation:

This CPT code is used for reporting the programming, interrogation, or follow-up of an implantable cardiac device (e.g., implantable cardioverter-defibrillator (ICD) or permanent pacemaker). 

The typical duration for such an encounter is 15-60 minutes, based on the design and complexity of the device and the programming requirements. If billing solely for professional interpretation, modifier 26 should be appended. The applicable ICD-10-CM code is Z45.01 (encounter for adjustment and management of cardiac pacemaker).

CPT Code 93798 – Cardiovascular Stress Testing (Supervised Program):

This CPT code is used to report supervised cardiovascular stress or cardiac rehabilitation sessions coming from an exercise regimen in which a clinician supervises and documents a patient’s physiologic response to structured exercise. Each session will last on average from 30 to 60 minutes, based on the prescribed program. The ICD-10-CM code is Z51.89.

Cardiology Billing Best Practices for Error-Free Claims

Verify Patient Insurance Coverage Before Procedures 

The first step before performing any cardiology procedure is to verify the patient’s insurance coverage in detail. This means checking benefits and eligibility, and seeing if any prior authorization is necessary, and whether everything is billed under facility or professional. 

It is also very important to check for coverage on any devices or supplies with the payer in advance. Be sure to refer to CMS and any Medicare Local Coverage Determinations (LCDs) before preauthorization, and payer-specific policies to avoid delays or denials on claims.

Accurate Medical Documentation 

The second most important step is to ensure any medical documentation is accurate, complete, and in compliance with payers and HIPAA. Clinicians should be documenting the clinical indication for all procedures, detailed operative or test times, all devices used, and have a signed physician interpretation. 

High-quality documentation will help affect the use of modifiers (e.g., 25, 22, 59) appropriately and help provide proof if an audit or review of claims requires evidence to show medical necessity.

Use Correct CPT and ICD-10 Codes 

The final step in the billing process is to code each procedure and diagnosis accurately. Precise coding requires coders to assign the appropriate CPT® and ICD-10-CM codes that accurately reflect the services performed at the highest level of specificity. 

Each coding element should be referenced against the American Medical Association (AMA) CPT® manual, NCCI edits, and CMS coverage requirements before submitting a claim. Correct coding allows for clean claims, quicker payments, and compliance with payer contracts and federal regulations.

Apply Appropriate Modifiers to Cardiology Codes 

• Modifier 25 is used for a significant, separately identifiable evaluation and management (E/M) service on the same day as another procedure. Documentation needs to include a significant history, exam, and medical decision-making.
• Modifier 51 is applied when more than one procedure is performed on the same encounter. Payer policy may differ in its use.
• Modifier 52 is used to report reduced services when a procedure has been partially performed. Documentation should clearly explain what led to the reduction in service.
• Modifier 53 is used in cases to show procedures were discontinued, and should include documentation on the record in regard to the reason for the discontinuation. 
• Modifier 59 identifies a distinct procedural service that is separate from other services on the same day. There should be caution for the use of Modifier 59 and consideration of the newer, more appropriate X{EPSU} modifiers.

Conclusion 

Accurate cardiology CPT codes and strict adherence to AMA/CMS/NCCI billing rules protect clinical integrity and revenue. Clinicians and coders must document procedural details (including realistic procedure times), match precise ICD-10 diagnoses, and apply modifiers only when supported by chart evidence. For practices seeking expert support, Nexus IO provides specialized cardiology billing services to ensure compliance and optimize reimbursement. Don’t forget to stay updated on the 2026 codification by regularly checking AMA CPT updates, CMS LCDs, and MAC bulletins.