Background: High-output heart failure (HOHF) is an underdiagnosed type of heart failure (HF) characterized by low systemic vascular resistance and high cardiac output.

Objective: This study sought to characterize the causes, mortality, and readmissions related to HOHF within the United States.

Methods: Data were collected from the Agency for Healthcare Research and Quality's Healthcare Cost and Utilization Project (HCUP) National Readmissions Database (NRD) from January 1, 2017, to November 30, 2019. We used the International Classification of Diseases, 10th revision (ICD-10), diagnostic codes to identify encounters with HOHF and heart failure with reduced ejection fraction (HFrEF).

Results: Of the total 5,080,985 encounters with HF, 3,897 hospitalizations (mean age 62.5 ± 17.9 years, 56.5% females) with HOHF and 5,077,088 hospitalizations with HFrEF were recorded. The most commonly associated putative etiologies of HOHF included pulmonary disease (19.8%), morbid obesity (9.9%), sepsis (9.6%), cirrhosis (8.9%), myelodysplastic syndrome (MDS) (7.9%), hyperthyroidism (5.5%), and sickle cell disease (3.3%). There was no significant difference in mortality rates [4.3% vs. 5.2%; odds ratio (OR) 0.9, 95% confidence interval (CI) 0.7-1.2] between HOHF and HFrEF. However, the 30-day readmission rate for HOHF was significantly lower than that for HFrEF (5.7% vs. 21.2%; OR 0.39, 95% CI 0.30-0.51). Cardiovascular (39.9%) followed by hematological (20.6%) complications accounted for the majority of 30-day readmissions in the HOHF group.

Conclusions: HOHF is an infrequently reported cardiovascular complication associated with noncardiovascular disorders and is encountered in 0.07% of all encounters with HF. Although comparable in-hospital mortality between studied cohorts was observed, raising awareness and timely recognition of this entity are warranted.