ICD-10 Code for Bradycardia: What Every Medical Coder Must Know

Accurate bradycardia coding hinges on understanding the critical distinction between symptom codes and definitive diagnoses. R00.1 (Bradycardia, unspecified) is the primary billable code for most bradycardia presentations, including sinus bradycardia. However, coders must recognize when documentation supports more specific codes like I49.5 (Sick sinus syndrome).

This guide covers essential code selection criteria, documentation requirements, drug-induced bradycardia sequencing rules, and common coding errors that trigger denials.

Quick ICD-10 Code Reference Table

The following table provides an at-a-glance reference for bradycardia-related ICD-10-CM codes. Use this as your primary reference when coding bradycardia encounters.

ICD-10 Code	Description	When to Use
R00.1	Bradycardia, unspecified	Sinus bradycardia, slow heartbeat, vagal bradycardia without specific etiology
I49.5	Sick sinus syndrome	Tachy-brady syndrome, documented sinus node dysfunction
P29.12	Neonatal bradycardia	Bradycardia in newborns (0-28 days of life)
I44.0	AV block, first degree	PR interval >200ms on ECG
I44.1	AV block, second degree	Mobitz Type I (Wenckebach) or Type II
I44.2	AV block, complete	Third-degree/complete heart block
I49.8	Other specified arrhythmias	Junctional/nodal rhythm disorders
Z86.79	Personal history of circulatory disease	Resolved bradycardia, history only

 

KEY INSIGHT: R00.1 is Billable Yes, R00.1 is a valid, billable ICD-10-CM code. It assigns to MS-DRG 308, 309, or 310 (Cardiac arrhythmia and conduction disorders) based on CC/MCC status. No separate sinus bradycardia code exists—it maps directly to R00.1.

Understanding R00.1: Bradycardia, Unspecified

R00.1 serves as the workhorse code for bradycardia coding. This Chapter 18 code (Signs and Symptoms) covers multiple clinical presentations:

"Applicable To" Terms for R00.1:

• Sinoatrial bradycardia
• Sinus bradycardia
• Slow heart beat
• Vagal bradycardia

CRITICAL INSTRUCTIONAL NOTES Type 1 Excludes: P29.12 (Neonatal bradycardia) - NEVER code R00.1 with P29.12 together. Type 2 Excludes: I47-I49 (Specified arrhythmias) - Both may coexist when documentation supports separate diagnoses. Use Additional Code: T36-T50 (5th/6th character 5) for drug-induced adverse effects.

Sinus Bradycardia ICD-10 Coding

A common question among coders: "What is the specific ICD-10 code for sinus bradycardia?" The answer: There is no separate code. Sinus bradycardia maps directly to R00.1 per the "Applicable To" terms in the ICD-10-CM Tabular List.

Bradycardia is clinically defined as a heart rate below 60 beats per minute at rest. However, physiologically normal rates below 60 BPM can occur in well-trained athletes and during sleep. Documentation should clearly indicate whether the bradycardia is pathological or incidental.

PRO TIP: When the provider documents "sinus bradycardia" without additional qualifiers, code R00.1. Do not search for a more specific code—it doesn't exist in ICD-10-CM.

Tachy-Brady Syndrome ICD-10 (Sick Sinus Syndrome)

When documentation specifies sick sinus syndrome or tachycardia-bradycardia syndrome, coders must use I49.5 instead of R00.1. This distinction significantly impacts medical necessity documentation and reimbursement, particularly for pacemaker procedures.

Clinical Findings Supporting I49.5:

• Alternating tachycardia/bradycardia patterns on ECG or Holter monitoring
• Sinus pauses exceeding 3 seconds
• Paroxysmal atrial fibrillation followed by sinus pauses
• Documented sinus node dysfunction

KEY INSIGHT: One Code for Tachy-Brady I49.5 captures the entire syndrome. Do NOT code both tachycardia and bradycardia separately when tachy-brady syndrome is documented. The "Applicable To" terms include tachycardia-bradycardia syndrome.

Junctional Bradycardia ICD-10 Coding

Junctional bradycardia presents a coding nuance. While I49.2 (Junctional premature depolarization) captures junctional rhythm disorders, the specific code selection depends on clinical context:

• AV-junctional (nodal) bradycardia: May be coded to R00.1 as an approximate synonym
• Nodal rhythm disorder: Consider I49.8 (Other specified cardiac arrhythmias)
• Junctional premature depolarization: Use I49.2

ICD-10 Code for Bradycardia in a Neonate

Neonatal bradycardia requires P29.12 exclusively for conditions originating in the perinatal period (through 28 days of life) documented on the newborn record. The Type 1 Excludes relationship between R00.1 and P29.12 prohibits using adult bradycardia codes for neonates.

NEONATAL CODING RULE P29.12 is the ONLY appropriate code for neonatal bradycardia. R00.1 must NEVER be used for patients 0-28 days of life. This is a Type 1 Excludes—the codes are mutually exclusive.

Drug-Induced Bradycardia: Sequencing Rules

Medication-induced bradycardia requires dual coding with strict sequencing rules that differ between adverse effects and poisoning scenarios.

Adverse Effects (Drug Properly Prescribed and Administered):

1. Code the manifestation FIRST (R00.1)
2. Add the adverse effect T-code with 5th/6th character "5"

Drug Class	Adverse Effect Code	Common Examples
Beta-Blockers	T44.7X5A	Metoprolol, Atenolol, Carvedilol
Calcium Channel Blockers	T46.1X5A	Verapamil, Diltiazem
Cardiac Glycosides	T46.0X5A	Digoxin, Digitalis

Poisoning (Overdose, Wrong Drug, Improper Use):

1. Code the poisoning T-code FIRST (5th/6th character 1-4 based on intent)
2. Then code the manifestation (R00.1)

PRO TIP: Accidental poisoning uses character "1" as the default when intent is undocumented or unknown. Missing T-codes is one of the most common audit findings.

History of Bradycardia ICD-10

When bradycardia has resolved and is no longer actively treated, Z86.79 (Personal history of other diseases of the circulatory system) captures the historical diagnosis. This code maps to history of bradycardia, cardiac arrhythmia, sick sinus syndrome, and heart block.

KEY INSIGHT: History Code Limitations Z86.79 is UNACCEPTABLE as a principal diagnosis. Use active diagnosis codes (R00.1 or I codes) when bradycardia is currently present. Patients with pacemakers whose bradycardia is controlled should have Z95.0 (Presence of cardiac pacemaker) coded alongside the history code.

Documentation Requirements for Accurate Coding

Complete documentation is essential for accurate bradycardia coding and medical necessity justification. Per AHA Coding Clinic guidance, R codes should not be used as principal diagnosis when a related definitive diagnosis has been established.

DOCUMENTATION CHECKLIST ☐ Specific heart rate value documented (e.g., "HR 48 bpm") ☐ ECG/EKG confirmation with rhythm identification ☐ Type specification (sinus, AV block, junctional, drug-induced) ☐ Symptom correlation (syncope, dizziness, fatigue linked to bradycardia) ☐ Underlying cause identification when applicable ☐ Medication review for drug-induced cases ☐ Chronicity documented (acute vs. chronic) ☐ Treatment plan and medical necessity for procedures

Medicare Pacemaker Coverage & Medical Necessity

CMS National Coverage Determination 20.8.3 directly impacts bradycardia coding for pacemaker procedures. Medicare covers permanent pacemakers for documented non-reversible symptomatic bradycardia due to sinus node dysfunction or second/third-degree AV block.

High-Denial Risk Scenarios (Non-Covered):

• Asymptomatic bradycardia
• Asymptomatic first-degree AV block
• Reversible causes (electrolyte abnormalities, temporary medication effects, hypothermia)

ICD-10 Codes Supporting Pacemaker Medical Necessity:

• I44.1 - Second-degree AV block
• I44.2 - Complete (third-degree) heart block
• I49.5 - Sick sinus syndrome
• Q24.6 - Congenital heart block

Seven Coding Errors That Trigger Denials

Avoid these common pitfalls that increase denial rates and audit exposure:

Common Error	✓ Correct Approach
Defaulting to R00.1 when SSS is documented	Use I49.5 for sick sinus/tachy-brady syndrome
Omitting drug-induced T-codes	Always add T36-T50 codes per ICD-10-CM instruction
Missing adverse effect sequencing	Code R00.1 first, then T-code for adverse effects
Using R00.1 with P29.12 together	Type 1 Excludes: never code both simultaneously
Coding symptoms with definitive diagnosis	Code the definitive diagnosis, not the symptom
Using Z86.79 for active bradycardia	History codes only for resolved conditions
Missing associated ECG findings	Code LBBB, PACs if documented on ECG

FY2024-2025 ICD-10-CM Updates

No significant changes to bradycardia-specific codes occurred in FY2024 (effective October 1, 2023) or FY2025 (effective October 1, 2024). The following codes remain active and billable with unchanged descriptions:

• R00.1 - Bradycardia, unspecified (unchanged)
• I49.5 - Sick sinus syndrome (unchanged)
• P29.12 - Neonatal bradycardia (unchanged)
• I44.x series - AV block codes (unchanged)

FY2025 added 252 new codes system-wide, including expansion of pulmonary embolism codes (I26 category), but cardiac arrhythmia categories remained stable. Current coding practices remain valid through October 2025.

KEY TAKEAWAYS R00.1 is the primary code for bradycardia, including sinus bradycardia—no separate code exists Use I49.5 for sick sinus syndrome and tachy-brady syndrome Always add T-codes for drug-induced bradycardia per ICD-10-CM instructions Never use R00.1 with P29.12 (neonatal bradycardia)—Type 1 Excludes Query providers when documentation supports greater specificity than stated