New onset of atrial fibrillation in acute coronary syndromes

Background: Acute coronary syndrome (ACS) and atrial fi brillation (AF) are common in the Portuguese population. In some cases, AF fi rst episode can occur in ACS context. Nevertheless, the impact of new-onset AF (nAF) in the setting of ACS seems to be associated with a poor prognosis. Objectives: To understand different characteristic in nAF patients with ACS and to evaluate the predictors of nAF. Methods: Multicenter retrospective study based on the Acute Coronary Syndrome Portuguese National Registry, including 29 851 patients admitted for ACS between 1/10/2010–4/09/2019, classifi ed according to the presence or absence of nAF during the hospitalization. Patients with previous AF were excluded. Results: nAF was identifi ed in 1067 patients (4.1%), mostly older, presenting more non-cardiovascular comorbidities, decreased left ventricular ejection fraction (LVEF) and a more complex coronary disease. nAF pa- tients received more anti-arrhythmic therapy, but just 21.5% had triple anti-thrombotic therapy and 30.3% had dual anti-thrombotic therapy. This group also presented high rates of in-hospital complications and death. Multiple logistic regression revealed that age >75 years old, previous stroke, higher Killip–Kimball class, haemoglobin <12g/dL and LVEF <50% were predictors of nAF in the setting of ACS. CHA 2 DS 2 -VASc score was a predictor of nAF in the setting of ACS (odds ratio 2.07, p <0.001), of cardiovascular re-admission ( p <0.001) and all-cause of re-admission ( p <0.001) at one year follow-up. Conclusions: Patients with nAF in the setting of ACS have a worse prognosis when compared to sinus rhythm patients. CHA 2 DS 2 -VASc score used for thromboembolic risk