Cardiology Billing Services: Diagnostic Codes, Catheterization Traps, and the TC/26 Split That Costs Practices Thousands

By Medtransic | February 15, 2026 | 16 min read | Updated: February 15, 2026

Quick Summary: Cardiology billing spans over 3,000 CPT codes — from routine EKGs to complex cardiac catheterizations and device implants. The technical/professional component split, artery-specific modifiers, and NCCI bundling rules create a coding environment where general billing companies consistently leave money on the table.

At Medtransic, cardiology is one of the specialties where we see the widest gap between what a practice should be collecting and what they actually collect. The reason is straightforward: cardiology billing involves over 3,000 CPT codes spanning diagnostic testing, imaging, interventional procedures, device management, and cardiac rehabilitation — and nearly every high-value service requires a technical/professional component split, specific modifiers, and payer-specific bundling awareness that general billing companies don't have.

An echocardiogram billed without the Doppler add-on. A cardiac catheterization where the left heart and right heart codes weren't separated correctly. A stress test interpretation denied because the professional component modifier was missing. An EKG performed during a routine physical that Medicare doesn't cover. These aren't edge cases — they represent the daily reality of cardiology billing, and each one is a revenue leak that compounds over months and years.

This guide covers the coding rules, modifier logic, and payer-specific traps that make cardiology billing one of the most complex specialties in medicine — and what your billing company should be doing to capture every dollar your practice earns.

Why Cardiology Billing Overwhelms General Billing Companies

Cardiology is unique because it straddles both high-volume diagnostics and high-value interventions. A typical cardiology practice performs dozens of EKGs, echocardiograms, and stress tests per week (each with relatively modest reimbursement but strict coding rules) alongside cardiac catheterizations, stent placements, and device implants that can generate $5,000 to $20,000+ per procedure.

This dual nature creates two distinct billing challenges. On the diagnostic side, the technical/professional component split (TC/26) must be applied correctly on every imaging and testing claim based on whether the cardiologist owns the equipment or is interpreting studies performed at a hospital. On the interventional side, catheterization and PCI coding requires artery-specific modifiers (LD, LC, RC), NCCI bundling awareness, and documentation of medical necessity that payers audit aggressively — a level of interventional coding complexity comparable to pain management billing.

Heart disease is the leading cause of death in America, which means cardiology practices operate at high volume. Industry data suggests practices lose 5 to 8% of annual revenue to denials and coding errors — highlighting why disciplined revenue cycle management is critical in a specialty where per-procedure reimbursement is among the highest in medicine. That's why Medtransic assigns dedicated cardiology coders to every cardiac practice we serve, not generalists who handle cardiology as one of twenty specialties.

The CPT Codes That Drive Cardiology Revenue

Cardiology CPT codes span diagnostic testing, imaging, interventional procedures, and device management. If your billing company can't explain the nuances within each category, they're not equipped for cardiac billing. For a broader reference, see our CPT codes cheat sheet.

Electrocardiograms (EKG/ECG)

Echocardiography

Stress Testing

Cardiac Catheterization and PCI

Device Monitoring

The TC/26 Split: The Most Expensive Mistake in Cardiology Billing

The technical/professional component split is the single most important concept in cardiology billing — and the one most frequently botched by general billing companies.

When a cardiologist performs and interprets a diagnostic test in their own office using their own equipment, they bill the global code (no modifier) which includes both the technical component (equipment, technician, supplies) and the professional component (physician interpretation and report). When the test is performed at a hospital or independent facility, the components are split: the facility bills the technical component (with -TC modifier) and the cardiologist bills the professional component (with -26 modifier).

The financial impact of getting this wrong is enormous. If your cardiologist interprets an echocardiogram performed at a hospital but your billing company submits the global code instead of -26, the claim will either be denied (because the hospital already billed the TC) or paid at the global rate when you're only entitled to the professional component — creating an overpayment that will be recouped in an audit. Conversely, if your practice owns the echo machine and performs the test in-office, billing only the -26 leaves the technical component revenue uncollected.

Medtransic tracks the place of service for every cardiology diagnostic claim and applies the correct TC/26 logic automatically. For practices that operate in both office and hospital settings — which is common in cardiology — this distinction must be made on a claim-by-claim basis. A billing company that defaults to one approach for all claims is either overbilling or underbilling on a significant portion of your diagnostic volume.

Cardiac Catheterization Coding: Where the Real Money Gets Lost

Cardiac catheterization and percutaneous coronary intervention (PCI) represent the highest-value procedures in cardiology — and the most complex to code correctly. A single cath lab session can involve right heart catheterization, left heart catheterization, coronary angiography, left ventriculography, and stent placement, each with its own CPT code and bundling rules.

Artery-Specific Modifiers for PCI

Medicare requires artery-specific modifiers on all PCI claims to identify which coronary vessel was treated. This is unique to cardiology and doesn't exist in any other specialty.

When PCI is performed on multiple vessels in the same session, the primary code (92928) gets the modifier for the first vessel, and the add-on code (92929) gets a different modifier for the additional vessel. Missing an artery modifier on a PCI claim results in an automatic denial — there is no exception. At Medtransic, we verify artery-modifier assignment against the cath lab report on every PCI claim.

What Bundles Into Catheterization

• Coronary angiography + left heart cath: When both are performed together, use 93458 (combined code). Do NOT bill 93452 + 93454 separately.
• Left ventriculography: Included in the catheterization code when performed during the same session. Not separately billable.
• Contrast injection: Bundled into the catheterization code. Do not bill separately for contrast administration.
• Closure device: Vascular closure devices used after catheterization are typically bundled. Check payer-specific policies — some commercial payers allow separate billing with HCPCS codes.
• Imaging supervision: Fluoroscopic guidance during catheterization is included in the procedure code. Do not bill 77002 or 77003 separately.

Modifier Rules That Make or Break Cardiology Claims

Cardiology uses more modifier types than nearly any other specialty. Between TC/26 splits, artery-specific modifiers, laterality, and same-day E/M billing, almost every claim requires at least one modifier — and many require two or three. For a full reference, see our modifiers guide.

At Medtransic, we maintain payer-specific modifier matrices for every major cardiology payer. Medicare, UnitedHealthcare, Aetna, and Blue Cross each have their own policies on -25 with same-day procedures, artery modifier requirements, and TC/26 split rules. Our cardiology coders verify every modifier against the procedure report and the payer's specific requirements before the claim is submitted.

The 7 Most Common Cardiology Denials (and How to Prevent Them)

Cardiology denial rates run 10 to 15% when billing is handled by non-specialist companies. Here are the seven denials we see most often and how Medtransic prevents each one.

1. Incorrect TC/26 split: Billing the global code when only the professional component was provided, or billing -26 when the practice performed the complete service. Prevention: Medtransic tracks place of service on every diagnostic claim and applies the correct TC/26 logic automatically.
2. Echo add-on codes billed with 93306: Billing Doppler add-ons (93320, 93325) alongside the complete echo code (93306) which already includes Doppler. This triggers a bundling denial. Prevention: Our claim scrubbing flags any Doppler add-on paired with 93306 before submission.
3. Missing artery modifier on PCI: Submitting stent placement (92928/92929) without the required LD, LC, RC, or RI modifier. Automatic denial with no appeal pathway without the modifier. Prevention: We verify artery-modifier assignment against the cath lab report on every PCI claim.
4. Combined cath billed as separate codes: Billing 93451 + 93452 separately when the combined code 93453 should be used. NCCI bundling edit triggers denial. Prevention: Medtransic's coding team reviews every cath lab report to determine the correct code combination.
5. Screening EKG billed to Medicare: Submitting 93000 with a screening or routine exam diagnosis code. Medicare does not cover screening EKGs — the test must be ordered for a documented symptom or condition. Prevention: We verify that every EKG claim has a supporting diagnostic ICD-10 code that establishes medical necessity.
6. Missing prior authorization for catheterization or device implant: High-value cardiac procedures frequently require pre-authorization, especially from commercial payers. A missing auth on a cath lab case can cost $3,000 to $15,000 in denied revenue. Prevention: Medtransic tracks auth requirements by payer and procedure, alerting the practice before the service date.
7. Modifier -25 denied on same-day E/M: Office visit billed on the same day as a stress test or echo with -25, but the documentation doesn't support a separately identifiable service. Prevention: The E/M must address a clinical issue beyond the test indication. We advise providers on documentation requirements that support defensible -25 billing in cardiology.

MIPS and Quality Reporting for Cardiology

Cardiology practices are heavily affected by the Merit-based Incentive Payment System (MIPS), which adjusts Medicare reimbursement based on quality, cost, improvement activities, and promoting interoperability performance. Poor MIPS scores can result in payment reductions of up to 9% — a significant hit to any cardiology practice's bottom line.

Cardiology-specific quality measures under MIPS include metrics for preventive care prescribing (statin therapy, anticoagulation for atrial fibrillation), procedural outcomes, and patient experience. Your billing company should be tracking which quality codes (G-codes and quality measure identifiers) need to be submitted alongside your procedure claims to satisfy MIPS reporting requirements.

Medtransic integrates MIPS quality reporting into our cardiology billing workflow so that quality measure data is captured and submitted alongside clinical claims — not as a separate, end-of-year scramble. This is also relevant for cardiac rehabilitation, where CMS requires the KX modifier for sessions beyond 36 and progress documentation showing measurable improvement to justify continued treatment.

What to Demand From a Cardiology Billing Service

Cardiology billing is not a specialty where a generalist can wing it. Here's what to ask when evaluating a billing partner.

• Cardiology-specific coding expertise: Ask how many cardiology practices they serve and what percentage of their coders have cardiac coding experience. If cardiology is a small fraction of their client base, they're a generalist.
• TC/26 split management: Ask them to explain their process for determining whether to bill the global code, -26, or -TC on diagnostic claims. If they don't immediately reference place of service and equipment ownership, they're not ready for cardiology.
• Cath lab coding process: Ask how they handle cardiac catheterization coding, combined vs. individual codes, and PCI artery-specific modifiers. If they can't name LD, LC, and RC, they shouldn't be touching your cath lab claims.
• Echo bundling knowledge: Ask which Doppler add-on codes can be billed with which base echo codes. If they don't know that 93320 bundles into 93306, they're overbilling or generating denials.
• MIPS reporting integration: Ask whether they integrate quality measure reporting into the billing workflow or handle it as a separate process.
• Denial rate across cardiology clients: Ask for their denial rate specifically for cardiac claims. Industry average is 10-15% — a specialist should be below 6%.
• Prior authorization tracking: Ask how they manage auth requirements for cath lab procedures and device implants. Do they maintain a payer-specific auth matrix?
• Coding update process: Ask how they stay current on annual CPT code changes, new Category III codes for emerging cardiac technologies, and payer LCD updates. Cardiology codes change every year — your billing company must keep up.

At Medtransic, cardiology billing is a core specialty — not an afterthought. Our cardiac coders review every procedure report, maintain payer-specific modifier matrices, manage TC/26 splits by place of service, and integrate MIPS quality reporting into the claims workflow. The result is clean claims, faster reimbursement, and a denial rate that stays well below the industry average.

• 97%+ Clean Claim Rate - Cardiology claims accepted on first submission
• <5% Denial Rate - Across Medtransic cardiology clients
• <30 days Average Days in AR - For cardiac practices using Medtransic
• 98%+ Net Collection Ratio - Revenue collected vs. owed