OBJECTIVE To evaluate the influence of gram-negative bacterial infection on the prognosis of patients with heart failure with reduced ejection fraction (HFrEF), and to explore its effects on biomarker dynamics, cardiac function recovery, rehospitalization rates and all-cause fatality rate.

METHODS Clinical data were retrospectively collected from 100 patients diagnosed with HFrEF and combined with gram-negative bacterial infection at the Second Affiliated Hospital of Guizhou Medical University and the Cardiovascular Medicine of the Army Medical Center of Chinese PLA from Jan. 2022 to Jan. 2024. Clinical baseline data, including demographic information, medical history and biomarkers interleukin-6 (IL-6), C-reactive protein (CRP), procalcitonin (PCT), brain natriuretic peptide (BNP), N-terminal pro-brain natriuretic peptide (NT-proBNP) and troponin were collected through follow-up visits for 12 months. Follow-up visits were conducted at discharge, 3 months, 6 months and 12 months, left ventricular ejection fraction (LVEF), NYHA classification (New York heart association functional classification for heart), rehospitalization status and all-cause fatality rate were recorded.

RESULTS Gram-negative bacterial infection significantly increased the rehospitalization and all-cause fatality rates in patients with HFrEF. The cumulative rehospitalization rate reached 45.00% within 12 months, and the all-cause fatality rate was 15.00% (P < 0.05). Inflammatory markers such as IL-6 and CRP were significantly elevated at baseline (P < 0.001) and decreased at discharge, while NT-proBNP levels were higher during the follow up period than those after the discharge, positively correlating with the numbers of rehospitalizations and fatality rates (r =0.752, P < 0.001). LVEF and NYHA classification improved in the short term but showed poor long-term prognosis.

CONCLUSIONS Gram-negative bacterial infection significantly affects the long-term prognosis of patients with HFrEF, exacerbating cardiac function damage through inflammatory responses, thus increases rehospitalization and fatality rates. This study provides new directions for clinical management, and emphasize the importance of early infection control.