CHA2DS2-VASC and HAS-BLED scores in the prediction of NVAF-related events in a population of critically ill patients

Background: non-valvular atrial fibrillation (NVAF) is the most common arrhythmia in clinical practice. Its risk increases with age and the presence of comorbidities. NVAF-related morbility is associated to thromboembolic events and, among patients undergoing to anticoagulant therapy, to haemorrhagic complications. Guidelines suggest stratifying the thrombotic risk with CHA2DS2-VASc score and the haemorrhagic risk with HAS-BLED score before initiating any anticoagulant treatment. These two scores share several items, and it is common to observe patients with both an increased thrombotic and haemorrhagic risk. This area represents a “grey zone” where guidelines are not able to suggest any evidence-based approach. Patients and Methods: we enrolled 519 consecutive, critically-ill subjects affected by permanent NVAF admitted to our Subintensive Medicine department. CHA2DS2-VASc score and HAS-BLED score were calculated at admission. For each patient, we evaluated age, sex, admission diagnosis, comorbidities, thromboembolic and haemorrhagic events. Results: mean age was 75.61(±11.92) years; males represented 50.3% of the sample; patients had a median of 2(0-6) comorbidities. We observed 38 haemorrhagic events and 80 thromboembolic events; HAS-BLED had a median of 2(0-5), CHA2-DS2-VASc score had a median of 3(0-6); CHA2DS2-VASc had an AUC of 0.56;95%CI:0.50-0:63(p=0.06); HAS-BLED had an AUC of 0.53;95%CI:0.44-0:62(p=0.53). Discussion: in this population of elderly patients admitted for critical illnesses, CHA2DS2-VASc and HAS-BLED scores have a limited predictive value for both thromboembolic and haemorrhagic events. Newer approaches based on machine learning and topological data analysis could better discriminate the risk factors of NVAF-related complications and give a more reliable prediction of thrombotic or haemorrhagic events.