Impact of early enteral nutrition on delirium prevention in patients with malnutrition concurrent with acute myocardial infarction

Background Delirium is a poor prognostic factor, particularly among older individuals. Malnutrition is a contributing factor to the development of delirium in patients with acute cardiovascular diseases. However, the role of delirium as a prognostic factor in patients with acute myocardial infarction (AMI) remains unclear, as does the association between malnutrition and delirium in these patients. Purpose This study aimed to investigate the impact of delirium on prognosis in patients with AMI, assess whether malnutrition predicts delirium in this population, and determine whether early enteral nutrition (EEN) can prevent delirium onset and improve nutritional status in patients with both malnutrition and AMI. Methods This retrospective observational study enrolled 361 consecutive patients with AMI. After excluding 38 in-hospital deaths, 323 patients with complete follow-up data were included for the evaluation all-cause mortality. The study also examined composite endpoints, including all-cause mortality, nonfatal stroke, nonfatal acute coronary syndrome, and heart failure. An Intensive Care Delirium score above 4 indicated delirium. Nutritional status was assessed using the geriatric nutritional risk index (GNRI), prognostic nutritional index (PNI), and controlling nutritional status (CONUT) scores. Results In total, 53 patients (16.4%) developed delirium. During a median follow-up of 31 months, Kaplan–Meier curves revealed significantly higher incidence rates of death and primary composite endpoints in the delirium group (all: p < 0.01, Figure). Particularly, the primary composite endpoint showed significantly worse outcomes in heart failure and nonfatal stroke for the delirium group (all: p < 0.01). At admission, patients in the delirium group had significantly lower GNRI, PNI, and CONUT scores (p < 0.01). Additionally, multivariate analysis revealed that the time to initiate enteral nutrition was a significant risk factor for delirium after adjusting for delirium-related factors (age, cognitive decline, sleep stabilizer use, and time to initiate enteral nutrition). Furthermore, the incidence of delirium significantly decreased when enteral nutrition was initiated within 2 days of admission (p < 0.01, Table). However, starting enteral nutrition after 3 days of admission (delayed enteral nutrition [DEN]) did not show the same benefit. A similar trend was observed in patients with malnutrition, defined as GNRI < 98 (p < 0.01), but not in well-nourished patients (p = 0.07). In patients with malnutrition, EEN also improved GNRI scores 1 month later, whereas DEN showed no significant difference. Conclusions Delirium is a poor prognostic factor in AMI. Malnutrition at admission is a significant predictor of delirium development. In patients with malnutrition, initiating enteral nutrition by the 2nd day of hospitalization significantly reduced the incidence of delirium and improved nutritional status.