New-onset atrial fibrillation (NOAF) frequently complicates acute coronary syndromes (ACS) leading to adverse short and long-term outcomes. The reported incidence ranges from 4 to 22% and a number of factors have consistently been shown to be associated with NOAF.

To determine the incidence of NOAF in a Tunisian population admitted for ACS, and to identify its predictive factors.

We performed a prospective observational cohort study including consecutive patients admitted to a single center for ACS over a one-year period. According to the NOAF occurred during hospitalization, the patients were divided into two groups: the NOAF and the non-NOAF group.

We included 402 patients. The incidence of NOAF was 9.7% in ACS Tunisian patients. NOAF was more frequent in older patients (P=0.001) and in those with previous renal failure (P<0.001), stroke (P=0.009) and ischemic cardiomyopathy (P=0.02). During hospitalization, patients with NOAF more often had heart failure (P=0.01) and higher values of serum uric acid (P=0.001), peak creatinine (P=0.001), CRP (P=0.02), neutrophil to lymphocyte ratio (P=0.04) and mean platelet volume (MPV, P=0.02). On echocardiography, they had greater indexed left atrial volume (P=0.02) and systolic arterial pulmonary pressure (P=0.03) while left ventricular ejection fraction (LVEF: 43±12% vs 48±10%, P=0.01) was significantly lower. Hemoglobin (119±1.8g/l vs 130±1.9g/l, P=0.001) was significantly lower in the NOAF group than the non-NOAF group. There were no significant differences in history of hypertension, diabetes, heart failure or pulmonary disease. In multivariate analysis, age (OR=1.08; P=0.02), MPV (OR=1.4; P=0.03), LVEF (OR=2; P=0.001) and indexed left atrial volume (OR=1.15; P=0.004) remained independent predictors of NOAF.

Age, LVEF, MPV and indexed left atrial volume are risk factors for incident NOAF in Tunisian patients admitted for ACS.