4A12X45Monitoring of Cardiac Electrical Activity, Ambulatory, External Approach
- Billable / Specific Code
4A12X45 is a billable ICD-10-PCS procedure code for Monitoring of Cardiac Electrical Activity, Ambulatory, External Approach. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027). The root operation Monitoring involves determining the level of a physiological or physical function repetitively over a period of time. The Alphabetic Index lists this code under Holter monitoring. In AHRQ's Clinical Classifications Software (CCSR), this procedure falls under Cardiac monitoring.
Code Identity
PCS Table Breakdown
Each ICD-10-PCS code is built from seven characters, each an axis of the procedure. Hover or tap the icons for the official CMS definitions.
| Position | Designation | Value | Meaning |
|---|---|---|---|
| 1 | Section | 4 | Measurement and Monitoring |
| 2 | Body System | A | Physiological Systems |
| 3 | Operation | 1 | Monitoring |
| 4 | BodySystem | 2 | Cardiac |
| 5 | Approach | X | External |
| 6 | Function/Device | 4 | Electrical Activity |
| 7 | Qualifier | 5 | Ambulatory |
In the ICD-10-PCS Alphabetic Index
The FY 2027 ICD-10-PCS Alphabetic Index refers to 4A12X45 as Holter monitoring. These index entries lead to this code:
To code holter monitoring, open the FY 2027 ICD-10-PCS Alphabetic Index at Holter monitoring. The entry lists 4A12X45 directly as a complete, billable code.
Clinical Classification (CCSR)
AHRQ groups this procedure code into these clinical categories.
Convert to ICD-9-PCS
Closest ICD-9-PCS equivalents for this code under the General Equivalence Mappings.
Similar Procedure Codes
Questions About 4A12X45
Is 4A12X45 a billable code?
Yes. This is a complete seven-character ICD-10-PCS code, specific enough to report Monitoring of Cardiac Electrical Activity, Ambulatory, External Approach on inpatient claims from October 1, 2026 through September 30, 2027.
What is the ICD-10-PCS code for holter monitoring?
The ICD-10-PCS Alphabetic Index lists Holter monitoring under code 4A12X45, Monitoring of Cardiac Electrical Activity, Ambulatory, External Approach, billable on inpatient claims in fiscal year 2027.
What do the characters in 4A12X45 mean?
The code breaks down character by character: the 1st character 4 is the Section (Measurement and Monitoring); the 2nd character A is the Body System (Physiological Systems); the 3rd character 1 is the Operation (Monitoring); the 4th character 2 is the BodySystem (Cardiac); the 5th character X is the Approach (External); the 6th character 4 is the Function/Device (Electrical Activity); the 7th character 5 is the Qualifier (Ambulatory).
What is the ICD-9-PCS equivalent of 4A12X45?
Under the General Equivalence Mappings, Monitoring of Cardiac Electrical Activity, Ambulatory, External Approach crosswalks to ICD-9-PCS 89.50 (Ambulatory cardiac monitoring). The mapping is approximate, so confirm it fits the documentation.
