We read the recently published article by Ferrera et al entitled “Usefulness of new-onset atrial fibrillation, as a strong predictor of heart failure and death in patients with native left-sided infective endocarditis.” We thank them for sharing their experience; however, we have some concerns about the article. The mortality associated with infective endocarditis (IE) is relatively high, and a rapid diagnosis and prediction of prognosis is essential to facilitate effective treatment. However, identifying patients at increased risk of adverse outcomes is challenging in IE because of the broad spectrum of the cardiac pathology and infecting microorganisms. Several biomarkers have been examined for their efficacy to predict outcome and assess prognosis of patients with IE. Although Ferrera et al showed that C-reactive protein levels were significantly different in patients with IE who develop new-onset atrial fibrillation, who remained in sinus rhythm and who had previous atrial fibrillation, they did not provided the data about other biomarkers. Previous studies showed that B-type natriuretic peptide (BNP) levels obtained on admission are significantly higher in patients with IE who died compared with survivors. These studies showed that the addition of troponin to BNP provided incremental prognostic value, and patients with IE who had concomitant elevations of troponin and BNP were at particularly high risk for poor outcomes. Moreover, none of the patients with either BNP or troponin elevation experienced the primary end points in these studies. Therefore, we would be grateful if the authors have and would provide the data regarding troponin and BNP levels on admission and their relation with new-onset atrial fibrillation in patients with IE.