Prognosis and risk factors of heart failure complicated with severe pneumonia after cardiovascular surgery

Backgrounds Heart failure (HF) is an advanced stage of various heart diseases and are at an elevated risk of pneumonia, which further worsens prognosis. Postoperative pneumonia is a life-threatening complication after cardiovascular surgery, significantly increasing mortality. However, data on risk factors for severe pneumonia in HF patients undergoing cardiovascular surgery remain limited. Methods This study included 194 HF patients who underwent cardiovascular surgery in the cardiovascular intensive care unit (CICU) from September 2024 to January 2025. Eligible participants were required to have undergone bacterial culture, drug sensitivity testing and respiratory pathogen nucleic acid testing during hospitalization. Multivariate logistic regression analyses were used to identify risk factors for severe pneumonia. Results Of the 194 patients, 55.67% had microbiologically positive results, with Klebsiella pneumoniae (36.4%) and Acinetobacter baumannii (21.2%) being the most common pathogens, and multidrug-resistant organisms (MDROs) accounting for 27.3% of isolates. Severe pneumonia occurred in 25.3% of HF patients, and these patients had a significantly higher mortality rate (51% vs. 8.3%, P < 0.001) compared to those without severe pneumonia. MDRO infection (adjusted OR: 5.114, 95% CI: 1.616–16.814) and end-stage HF (adjusted OR: 5.526, 95% CI: 1.397–21.859) as independent risk factors for severe pneumonia. Conclusion This study highlights that MDRO infection and end-stage HF are critical independent risk factors for severe pneumonia in HF patients after cardiovascular surgery, with severe pneumonia significantly increasing mortality. These findings emphasize the need for targeted strategies to improve clinical outcomes.