Study Highlights Limitations of ICD-10 Codes in Heart Failure Studies


Marc Bonaca, MD, discusses an AHA 2023 study he led examining trends in discordance between LVEF and ICD-10 codes used in heart failure hospitalizations.

Results of a study looking at International Classification of Diseases (ICD)-10 codes suggests researchers and clinicians should be cautious when interpreting data from analyses reliant on ICD-10 codes for heart failure.

Led by Marc Bonaca, MD, of the University of Colorado Aurora Health, data from the study, which was presented at American Heart Association (AHA) Scientific Sessions 2023, demonstrates varying levels of concordance between left ventricular ejection reaction and ICD-10 for heart failure hospitalizations.

“I think the lesson for us is that you have to be really careful with real world data,” explained Bonaca, in an interview with HCPLive Cardiology. “We have to recognize that CPT codes or billing codes, ICD codes, are for billing and not for science. That doesn't mean they're not useful, but when you when you look, you have to really validate that what you're sampling over time reflects what you intended to sample.”

With an interest in examining the specificity of ICD-10 codes for case identification, Bonaca and a team of colleagues designed the current study to assess the relationship between left ventricular ejection fraction and assigned ICD-10 code using a real-world dataset. Through a cross-sectional analysis of patients admitted from January 1, 2018 through October 1, 2022, with a principal diagnosis of heart failure, which results in a cohort off 61,238 heart failure hospitalizations. Of these, 49,772 had available data on left ventricular ejection fraction.

For the purpose of analysis, investigators defined as having one of the following ICD-10 codes: I50.2, systolic heart failure; I50.3, diastolic heart failure; I50.4, combined systolic and diastolic heart failure; I11.0, hypertensive heart disease with heart failure; and I13.0 and I13.2, hypertensive heart disease with heart failure and chronic kidney disease.

Upon analysis, results suggested most patients admitted with systolic heart failure as well as systolic and diastolic heart failure had an LVEF of 40% or less (86.2% and 74.8%, respectively). Investigators noted a similar trend was observed for patients admitted with diastolic heart failure, with 94.0% of this group having an ejection fraction of 50% or greater.

In contrast, those admitted with hypertensive heart disease with heart failure and hypertensive heart disease with heart failure and chronic kidney disease, which made up 36.3% and 52.9% of the cohort, respectively, a greater degree of variation was observed for ejection fraction distribution.

For more insight into the results of this study and how it might inform future research efforts, the HCPLive Cardiology editorial team sat down with Bonaca as part of to learn more. A portion of that interview can be found below.

Relevant disclosures for Bonaca include Medtronic, Pfizer, Abbott Laboratories, Adamis Pharmaceuticals Corporation, Agios Pharmaceuticals, Inc., and others.


  1. Gluckman T, Chiu ST, Rider D, et al. Relationship Between Left Ventricular Ejection Fraction and ICD-10 Codes Among Patients Hospitalized for Heart Failure. Paper presented at: American Heart Association Scientific Sessions 2023; November 10 - 13; Philadelphia, PA. Accessed November 10, 2023.
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