Background: Atrial fibrillation (AF) and nutrition status abnormalities are two of the most significant epidemics in current health care.

Aim: The aim of this study was to determine the relationship between the prevalence and outcome of AF, and the parameters of nutritional status among consecutive, real-life patients hospitalised in a university hospital.

Methods: Analysis of the medical documentation of 4930 consecutive patients aged ≥ 18 years hospitalised for more than one day with diagnoses of cardiovascular disorders.

Results: Patients admitted with a diagnosis of AF (n = 512) compared to their counterparts without AF less frequently had an NRS-2002 score ≥ 3, normal range of body mass index (BMI), higher blood haemoglobin, and lower low density lipoprotein cholesterol (LDL-C) concentration. In logistic regression analysis, the risk of a hospitalisation due to AF was negatively related to BMI, NRS-2002 score, and the value of the difference between ideal and actual body mass. Urgent admission and having an NRS-2002 score ≥ 3 remained the only significant variables determining the risk of in-hospital death. Blood concentration of LDL-C and urgent admission were the only significant variables determining risk of 30-day rehospitalisation in the studied population.

Conclusions: Inpatients with AF had a lower prevalence of normal body mass. Patients with an AF diagnosis had different risk factors for in-hospital death and 30-day rehospitalisation than their counterparts with diagnosis of cardiovascular diseases but without AF; however, the parameters of nutritional status played an important role in both patient groups. The obesity and cholesterol paradoxes were also observed.