RBBB ICD-10-CM Codes | 2025

What are RBBB ICD-10-CM Codes?

Right bundle branch block (RBBB) is a cardiac conduction disorder that affects the electrical pathways in the heart. This bundle branch block delays the electrical impulse reaching the right ventricle, resulting in asynchronous contraction between the heart's ventricles.

RBBB is classified under conduction disorders in the ICD-10-CM coding system and is often found during routine electrocardiogram (ECG) screenings. On ECG, it presents as a widened QRS complex (>120 ms), especially in leads V1 and V2.

RBBB may occur as an isolated condition or in conjunction with heart disease, myocardial infarction (heart attack), cardiomyopathy, pulmonary embolism, or atrial fibrillation. It may also appear in patients with a pacemaker, those who’ve experienced cardiac arrest, or as part of more complex bifascicular block or pre-excitation syndromes.

Here are the correct and billable ICD-10-CM codes for RBBB:

• I45.10 – Unspecified right bundle-branch block: Use this code when RBBB is present, but the type or cause is not further defined. It is the standard diagnosis code for nonspecific or incidental findings of RBBB.
• I45.19 – Other right bundle-branch block: Apply this code when documentation supports other specified forms of right bundle-branch block not fitting the criteria for unspecified (e.g., persistent, associated with structural changes, or seen in conjunction with other conduction abnormalities).

It is important to remember not to use codes like I44.21–I44.32, which previously attempted to describe subtypes such as familial, ischemic, or degenerative bundle branch blocks. These are not included in the 2025 ICD-10-CM list.

Which RBBB ICD-10-CM Codes are billable?

Both I45.10 – Unspecified right bundle-branch block and I45.19 – Other right bundle-branch block are billable.

Clinical information

• Pathophysiology: RBBB causes a delay in impulse transmission through the right bundle, leading to an incomplete or complete block in electrical conduction. This affects the ventricles' coordination and is part of broader conduction disorders categorized under diseases of the circulatory system.
• Diagnosis: RBBB is diagnosed using an electrocardiogram (ECG). Typical findings include:
  • QRS duration > 120 milliseconds
  • rsR’ pattern in V1
  • Wide S wave in leads I and V6
• Causes: Common causes are:
  • Idiopathic conduction degeneration (especially in older adults)
  • Heart failure
  • Cardiomyopathy
  • Myocardial infarction
  • Congenital heart disease
  • Posterior fascicular block or anterior fascicular block (as components of bifascicular block)
• Symptoms: Many patients with RBBB are asymptomatic, but when symptoms are present, they may include:
  • Chest pain
  • Shortness of breath
  • Syncope (especially when associated with atrioventricular block or more complex conduction disease)
• Treatment: Isolated RBBB usually requires no treatment. If linked to acute conditions like cardiac arrest, paroxysmal tachycardia, or new onset heart disease, the focus is on:
  • Treating the underlying condition
  • Monitoring in hospital settings
  • Considering pacemaker implantation if advanced atrioventricular block or symptomatic intraventricular conduction delays are present

To ensure sufficient justification for these codes:

• Clearly document the patient’s symptoms and any underlying diseases of the circulatory system.
• Support the principal diagnosis with ECG findings and related tests.
• Link any treatment, such as evaluation in an acute care hospital, to associated heart block, fascicular block, or atrial arrhythmias.

While RBBB falls under the I45.1 series, it's important to be familiar with other ICD-10-CM codes for related conduction disorders, including bundle branch and fascicular blocks:

• I44.1 – First degree atrioventricular block
• I44.4 – Left anterior fascicular block
• I44.7 – Other and unspecified fascicular block
• I45.0 – Right fascicular block (rarely used today)
• I45.2 – Left bundle-branch block
• I45.3 – Bifascicular block
• I45.8 – Other specified heart block
• I45.9 – Bundle branch block NOS (not otherwise specified)
• I45.6 – Pre-excitation syndrome

Synonyms include

• Right bundle branch conduction delay
• Right bundle branch pathway dysfunction
• Right bundle branch syndrome
• Right-sided bundle branch block
• Right ventricular bundle branch block
• Right-sided conduction delay
• Right bundle branch aberration
• Right fascicular block
• Right bundle branch heart conduction disorder