New-onset atrial fibrillation during acute coronary syndromes: predictors and prognosis

New-onset atrial fibrillation (AF) frequently complicates myocardial infarction, with an incidence of 6-21%.

To assess the predictors and prognosis of new-onset AF during acute coronary syndromes (ACS).

We performed a retrospective observational cohort study including 902 consecutive patients (mean age 64 years, 77.5% male) admitted to a single center over a two-year period, with a six-month follow-up.

AF rhythm was identified in 13.8% patients, of whom 73.3% presented new-onset AF and 26.8% pre-existing AF. New-onset AF was more frequent in older (p<0.001) and hypertensive patients (p=0.001) and in those with previous valvular heart disease (p<0.001) and coronary artery bypass grafting (p=0.049). During hospitalization, patients with new-onset AF more often had respiratory infection (p=0.002) and heart failure (p<0.001), and higher values of NT-proBNP (p=0.007) and peak creatinine (p=0.001). On echocardiography they had greater left atrial (LA) diameter (p<0.001) and more frequent significant mitral regurgitation (p<0.001) and left ventricular ejection fraction (LVEF) ≤40% (p<0.001) and were less likely to have significant coronary lesions (p=0.009) or to have undergone coronary revascularization (p<0.001). In multivariate analysis, age (OR 1.06, p=0.021), LVEF ≤40% (OR 4.91, p=0.002) and LA diameter (OR 1.14, p=0.008) remained independent predictors of new-onset AF. Together with age, diabetes and maximum Killip class, this arrhythmia was an independent predictor of overall mortality (OR 3.11, p=0.032).

Age, LVEF ≤40% and LA diameter are independent predictors of new-onset AF during ACS. This arrhythmia is associated with higher overall mortality (in-hospital and in follow-up).