Diagnostic Endocardial Electrical Stimulation (Pacing) — NCD 104 | CMS Coverage Update

TL;DR: The Centers for Medicare & Medicaid Services modified NCD 104 governing diagnostic endocardial electrical stimulation (EES), with an effective date of March 7, 2026. Here's what billing teams need to know.

CMS diagnostic endocardial electrical stimulation coverage policy under NCD 104 in the Medicare system covers EES for patients with severe cardiac arrhythmias. This policy governs procedures performed across outpatient hospital, physician services, and other diagnostic test benefit categories. The policy does not list specific CPT or HCPCS codes — which creates a documentation problem your team needs to address before March 7, 2026.

Quick-Reference Table

CMS Diagnostic Endocardial Electrical Stimulation Coverage Criteria and Medical Necessity Requirements 2026

The coverage policy under NCD 104 is narrow by design. The Centers for Medicare & Medicaid Services covers EES — also called programmed electrical stimulation of the heart — only for patients with severe cardiac arrhythmias. That's the entire medical necessity threshold, stated plainly.

What makes this interesting is what CMS chose to include in the procedure description. EES requires intracardiac electrode catheters, intracardiac and extracardiac recordings, and a stimulator device. Two to six multipolar electrode catheters are inserted percutaneously — usually through the femoral veins — and advanced to the heart under fluoroscopic control. Other venous or arterial routes are also permitted.

The principal use CMS recognizes is diagnosis and treatment of sustained ventricular tachycardia. But the policy also covers EES for other complex arrhythmias, conduction defects, and evaluation after cardiac arrest. This is broader than some billing teams realize. If your cardiologists are using EES only for VT workups, you may be leaving covered indications on the table.

One specific exclusion is baked into the procedure description itself. An intracardiac His bundle cardiogram is typically obtained during EES. CMS will not recognize a separate charge for it. The His bundle cardiogram is considered bundled — no separate billing, no separate line item. If your charge capture currently breaks this out, stop it before the March 7, 2026 effective date.

EES is also used to identify patients at risk of sudden arrhythmic death. CMS acknowledges this as a legitimate clinical use within the policy. That matters for your documentation strategy — the clinical reason needs to map to severe arrhythmia risk, not just a general cardiac workup.

Prior authorization requirements are not explicitly called out in NCD 104 for EES. That doesn't mean your Medicare Advantage plans won't require prior auth — they often impose requirements beyond what the NCD specifies. Verify with each MA plan separately, and check whether your MAC has a local coverage determination that adds prior authorization requirements on top of this national policy. LCDs from your Medicare Administrative Contractor can be stricter than the NCD, and they're the ones who adjudicate your claims.

The coverage policy spans three benefit categories: diagnostic services in outpatient hospital, diagnostic tests (other), and physicians' services. That means this NCD applies whether you're billing in a facility or professional setting. Your hospital outpatient billing team and your physician billing team both need to know this policy.

CMS Diagnostic Endocardial Electrical Stimulation Exclusions and Non-Covered Indications

NCD 104 does not contain a formal experimental or investigational designation for any specific EES indication. But the coverage boundary is clear: EES is covered for severe cardiac arrhythmias. Anything outside that definition is not covered.

This is where claim denial risk lives. If a physician orders EES for a patient who doesn't have a documented severe arrhythmia, that claim will not survive a coverage review. The diagnosis code on the claim has to support the severity threshold CMS requires.

CMS is also explicit about the His bundle cardiogram. It's listed as a non-separately-billable service, not as a covered add-on. There's no gray area here — bill it separately and you're billing for a non-covered service. That's a compliance issue, not just a denial issue.

Coverage Indications at a Glance

CMS Diagnostic Endocardial Electrical Stimulation Billing Guidelines and Action Items 2026

CPT, HCPCS, and ICD-10 Codes for Diagnostic Endocardial Electrical Stimulation Under NCD 104

NCD 104 does not list specific CPT, HCPCS, or ICD-10 codes. This is not an oversight — some national coverage determinations describe covered procedures at a clinical level without tying them to specific codes. The absence of a code list means your coding team carries more responsibility, not less.

What This Means for Endocardial Electrical Stimulation Billing

NCD 104 lists no CPT or HCPCS codes. Your coding team must identify the correct codes through their own coding resources and MAC guidance. Do not use this blog post as a source for code selection — we do not provide code suggestions, ranges, or examples for this policy.

The lack of a code list in NCD 104 creates a specific risk: your coders may be applying codes that technically describe the procedure but aren't the ones your MAC recognizes for EES coverage. A mismatch between code and NCD results in a denial that looks like a coverage issue but is actually a code selection issue. These are hard to catch without a targeted audit.

The same applies to ICD-10-CM codes. NCD 104 does not identify specific ICD-10 codes. "Severe cardiac arrhythmia" is a clinical standard, not a specific ICD-10 code. Work with your clinical documentation improvement team to build a crosswalk using their coding resources and MAC guidance. Your medical director and compliance officer should sign off on the final list.