Early Vs Late New-Onset Atrial Fibrillation in STEMI Patients: Pathophysiological Mechanisms and Relationship with In-Hospital Outcomes

Abstract Background New-onset atrial fibrillation (NOAF) represents the most common supraventricular arrhythmia in the setting of ST-elevation myocardial infarction (STEMI), with up to 21% patients affected. The occurrence of NOAF has clinical relevance as previous studies showed that atrial fibrillation (AF), whether pre-existent to the admission or newly developed during STEMI hospitalization, is associated with worse short- and long-term prognosis. More recently, two distinct phenotypes of NOAF have been described, such as early NOAF (EAF) for AF occurring within 24 h from STEMI, and late NOAF (LAF) for AF onset beyond 24h. The mechanisms underlying EAF or LAF are poorly described. Objective To investigate atrial branches occlusion and EAF or LAF onset in STEMI patients undergoing primary percutaneous coronary intervention. Methods Retrospective cohort study including 155 STEMI patients. Patients were divided into 3 groups: sinus rhythm (SR), EAF or LAF. Clinical characteristics, angiographic features including occlusion of atrial branches, namely ramus ostia cavae superioris (ROCS), atrio-ventricular node artery (AVNA), right intermediate atrial artery (RIAA) and left intermediate atrial artery (LIAA), were assessed (Figure 1). We also investigated in-hospital adverse events (AEs) and death. Results Mean age was 63.8±11.9 years; 78.7% of men. NOAF was detected in 22 (14.2%) patients: 10 (6.4%) EAF and 12 LAF (7.7%). Compared to EAF, LAF patients were older (p=0.013), with higher GRACE risk score (p=0.014) and Killip class (p=0.015), depressed ejection fraction (p=0.007), elevated filling pressures (p=0.029), higher c-reactive protein (p=0.014) and more TIMI flow <3 (p=0.015). Compared to SR, EAF was associated with higher prevalence of occluded ROCS (p=0.010), AVNA (p=0.005) and RIAA (p<0.001) (Figure 2). Moreover, EAF patients had more frequently ≥2 diseased atrial branches than SR (19.5%, p<0.001) and LAF (25%, p<0.030) patients. In LAF patients, a higher incidence of AEs (p=0.019 vs SR; p=0.029 vs EAF) and death (p=0.004 vs SR) was found. Conclusions The occlusion of atrial branches is associated with early but not late NOAF following STEMI. LAF patients had worse in-hospital AEs and mortality. Funding Acknowledgement Type of funding sources: None. Anatomy of atrial branchesInvolvement of atrial branches