Association between comorbid cardiomyopathy and composite endpoints of patients with congestive heart failure in the intensive care unit: a retrospective cohort study

BACKGROUND: Congestive heart failure (HF) is a common condition in the intensive care unit (ICU). Cardiomyopathy is an important etiological factor in HF. However, few studies have explored the effect of cardiomyopathy on the prognosis of HF. This study explored the association between comorbid cardiomyopathy and the outcomes of critically ill patients with congestive HF. METHODS: A retrospective cohort study was performed using data extracted from Medical Information Mart for Intensive Care IV (MIMIC-IV) database. All adult patients with the first ICU admission were enrolled as participants but those diagnosed with cardiomyopathy alone were excluded. The demographics, comorbidities, vital signs, laboratory tests, scoring systems, and treatments of patients were extracted to further analyze. The composite endpoints included in-hospital mortality, cardiac arrest, and re-admission to the ICU. The association between cardiomyopathy comorbidity and the composite endpoints was assessed using propensity-score matching (PSM) and multivariable logistic regression models. RESULTS: A total of 27,901 critically ill patients were enrolled, including 1,023 patients diagnosed with cardiomyopathy and congestive HF. The average age of the cohort was 64.37±17.36 years, and 58.13% of the patients were men. The ethnicity of patients was mainly white (64.67%). Multivariable logistic regression analyses found the risk of composite endpoints in patients with cardiomyopathy was higher than other groups [odds ratio (OR) =1.87; 95% confidence interval (CI): 1.62–2.15; P<0.001]. Compared to patients with congestive HF alone (OR =1.43; 95% CI: 1.26–1.62; P<0.001), patients with cardiomyopathy had a similar risk of in-hospital death (OR =1.35; 95% CI: 1.06–1.71; P=0.014). Moreover, the risks of cardiac arrest (OR =1.53; 95% CI: 1.01–2.34; P=0.029) and re-admission to the ICU (OR =1.74; 95% CI: 1.39–2.17; P<0.001) were both higher in patients with cardiomyopathy than other groups. After PSM, the risk of composite endpoints was still higher in patients with cardiomyopathy (OR =1.64; 95% CI: 1.33–2.02; P<0.001). The association was consistent among patients admitted to the coronary care unit (CCU) and medical ICU (MICU)/surgical ICU (SICU). CONCLUSIONS: Comorbid cardiomyopathy increased the risk of composite endpoints in patients with congestive HF admitted to the ICU. Cardiomyopathy is related to the poor outcomes of critically ill patients with congestive HF.