This population-based study retrospectively investigated 18,179 ICU patients with AF. Two nomograms were developed and validated to gauge the risk of AHF in those patients. The nomograms contained 10 variables: age; respiratory rate; fluid management; mean corpuscular haemoglobin concentration (MCHC); bicarbonate; blood urea nitrogen (BUN); chloride; and the Charlson, LODS, and SAPS II scores. Both nomograms had good clinical performance. ROC analysis of the training and validation cohorts revealed AUCs of 0.768 and 0.763, respectively, for nomogram 1; these AUCs were 0.696 and 0.692 for nomogram 2. The findings suggest that our models are sufficiently predictive.
The relationship between AF and heart failure remains an area of study [21]. Ischemia, blood pressure, blood glucose, age, and atherosclerosis are generally regarded as risk factors for both diseases [21, 22]. The incidences of heart failure and AF both gradually increase with age [23], consistent with our findings.
When heart failure occurs, the respiratory rate increases. Breathing adjustments affect the treatment of heart failure [24]. This study recognised respiratory rate as a risk factor for AHF in patients with AF, similar to the results in some previous studies [25]. Input and output volumes are important for evaluating the degree of heart failure [26]; reductions in output and input are termed fluid management. Our model 1 showed that greater fluid management increases the risk of AHF. Relative erythrocyte hypochromia, which manifests as a low MCHC, affects the onset of AHF [27]; a decrease in the MCHC corresponds to an increase in the risk of AHF. The serum bicarbonate level also significantly increases in patients with AHF, and it can serve as a predictive indicator. BUN is related to renal function and is not an independent risk factor for AHF, although it can serve as a warning signal. Chloride is associated with cardiorenal and neuroendocrine systems [28], and many studies regard the chloride level as a prognostic marker [29]. The present study identified it as a predictive factor, such that a decrease in chlorine was accompanied by an increase in the incidence of AHF. Additionally, the present study utilised three scoring systems to establish the second nomogram. The use of model 2 requires some medical expertise; thus, it is designed for clinicians. Although nomogram 2 is less accurate and predictive compared with nomogram 1, it can provide validation for clinical decision-making.
This study had some limitations. First, all data was obtained from the MIMIC-IV database. Incomplete records and possible data errors may have reduced model accuracy. Second, this was a single-centre retrospective study with internal validation alone; external validation is needed to confirm the reliability of the results. Third, blood lipids were not included in the study due to the lack of corresponding records in the MIMIC-IV database. Blood lipids are important risk factors for cardiovascular diseases [30], and further research is needed concerning their implications. Fourth, the types and severity of AF were not considered; thus, we did not determine the risk of AHF at each AF severity level. Additionally, all types of AHF were pooled in our analyses. Finally, our nomograms may predict the possibility of AHF in patients with AF, but they cannot determine whether interventions should be promptly applied.