ICD-10-CM 2027
ICD-10 code for QT interval prolongation syndrome
From the official ICD-10-CM alphabetic index entry “Syndrome › QT interval prolongation”. Page updated September 29, 2026.
About coding QT interval prolongation syndrome
The ICD-10-CM code for QT interval prolongation syndrome is I45.81 (Long QT syndrome).
Within I45.8 (other specified conduction disorders), I45.81 is specifically for long QT syndrome. Related codes cover other specified conduction disorders (I45.89).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
In MS-DRG v44.0, it is part of the grouping logic for DRG 308 (Cardiac Arrhythmia and Conduction Disorders with MCC, relative weight 1.1806), DRG 309 (Cardiac Arrhythmia and Conduction Disorders with CC, relative weight 0.7316) and DRG 310 (Cardiac Arrhythmia and Conduction Disorders without CC/MCC, relative weight 0.568), in MDC 05 (Diseases and Disorders of the Circulatory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about QT interval prolongation syndrome ICD-10 codes
What is the ICD-10 code for QT interval prolongation syndrome?
- I45.81 — Long QT syndrome.
Is I45.81 billable?
- Yes. I45.81 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can I45.81 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict I45.81 as a principal diagnosis.
Is I45.81 a CC or MCC?
- No. I45.81 is neither a CC nor an MCC under MS-DRG v44.0.