Abstract Body (Do not enter title and authors here): Introduction
The prevalence of heart failure with improved ejection fraction (HFimpEF) is growing. The association of ejection fraction recovery and changes in health status has not been previously reported.

Hypothesis
We hypothesized patient-reported health status (HS) will be significantly better among patients with HFimpEF compared with those with HF with reduced ejection fraction (HFrEF) or HF with mid-range/preserved ejection fraction (HFmrEF/HFpEF).

Methods
We identified patients with HF with at least 2 encounters with the Stanford cardiology clinic who completed a routinely collected Kansas City Cardiomyopathy Questionnaire (KCCQ)-12 from 8/2020 to10/2023. HFimpEF was defined as most recent EF>40% from a preceding echocardiogram > 30 days prior with EF<40%. We compared patient sociodemographic and clinical characteristics across EF classifications. We analyzed KCCQ-12 Overall Summary Score (OSS) across EF classifications with and without adjustment for patient characteristics via multivariable linear regression, from which we calculated the R² to determine the impact of clinical characteristics on variation in HS among patients with HFimpEF.

Results/Data
A total of 2,519 patients were included in this analysis, of which 18.7% had HFimpEF, 55.7% had HFmrEF/HFpEF, and 25.6% had HFrEF. Median KCCQ-12 OSS was 80.3, 73.9, and 80.8 for HFimpEF, HFrEF and HFmr/HFpEF patients, respectively. Patients with HFimpEF were less likely to be women compared with patients with HFmrEF/HFpEF (41% vs 58%, p<0.01). There was substantial overlap in the KCCQ-12 OSS across EF classifications (Figure). KCCQ-12 OSS score was 5.2 points lower among patients with HFrEF compared with patients with HFimpEF [(95% CI: -8.2 to -2.3); p=0.01] but patients with HFimpEF had similar scores to those with HFmrEF/HFpEF [-1.1 (95% CI: -3.7 to 1.6); p=0.43]. Among patients with HFimpEF, a multivariable regression model explained 16% of the variation in the KCCQ-12 OSS.

Conclusions
Despite improvement in EF, patients with HFimpEF continue to have impaired HS that is similar to patients with HFpEF and HFmrEF. Further research is needed to better understand impaired HS and to identify interventions to improve health status among patients with HFimpEF.