ICD-10 Code for Congestive Heart Failure
The primary ICD-10 code for congestive heart failure is I50, with specific subcodes depending on the type and severity of heart failure.
Core ICD-10 Coding Structure
The I50.x series encompasses all heart failure diagnoses, with the following key subcodes used in clinical practice and research:
- I50.2 – Systolic (congestive) heart failure 1, 2
- I50.3 – Diastolic (congestive) heart failure 1, 2
- I50.4 – Combined systolic and diastolic heart failure 2
- I50.9 – Heart failure, unspecified 1, 3
Additional related codes include:
- I11.0 – Hypertensive heart disease with heart failure 2
- I13.0 and I13.2 – Hypertensive heart and chronic kidney disease with heart failure 2
Coding Accuracy and Clinical Validation
When using I50.x codes in the primary diagnosis position, the positive predictive value for acute heart failure hospitalization is 98%, making it highly reliable for identifying true heart failure cases 1. However, accuracy drops to 66% when the code appears in the first or second position 1.
Ejection Fraction-Specific Coding
The relationship between ICD-10 codes and left ventricular ejection fraction (LVEF) shows important patterns:
- I50.2 (systolic HF) has a 90% positive predictive value for LVEF ≤50% and 72% for LVEF ≤40%, with 86.2% of hospitalized patients actually having LVEF ≤40% 1, 2
- I50.3 (diastolic HF) has a 92% positive predictive value for LVEF >50%, with 94% of hospitalized patients having preserved ejection fraction 1, 2
- I50.4 (combined dysfunction) shows 74.8% of patients have LVEF ≤40% 2
Important Coding Caveats
Codes I50.4 (combined) and I50.9 (unspecified) poorly predict specific heart failure phenotypes and should be avoided when ejection fraction data are available 1. The hypertensive heart disease codes (I11.0, I13.0, I13.2) represent the majority of heart failure hospitalizations but show a much wider range of ejection fractions, making them less specific for phenotyping 2.
Optimizing Code Selection in Practice
To maximize coding accuracy, restrict analyses to primary diagnosis codes or codes assigned by cardiology departments, which increases positive predictive value to 88-95% 3, 4. When quantitative ejection fraction is documented, use I50.2 for reduced ejection fraction or I50.3 for preserved ejection fraction rather than unspecified codes 1.
The overall sensitivity of I50.x codes for capturing all heart failure cases is only 64%, meaning approximately one-third of true heart failure patients may not be coded appropriately 4. Sensitivity is higher in cardiology departments compared to general medical wards 4.
Clinical Context
While ICD-10 codes are administrative tools, they must align with clinical diagnostic criteria. Heart failure diagnosis requires the triad of characteristic symptoms (dyspnea, fatigue, exercise intolerance), objective evidence of cardiac dysfunction (typically LVEF ≤40% for HFrEF), and elevated natriuretic peptides 5. The codes should reflect this clinical reality rather than being assigned based solely on symptoms or single test results 3, 4.