Although the authors17 report a reduction in the composite outcome of in-hospital deaths and embolic events with early surgery (3% versus 23%), the differences between the 2 groups were driven by a significant decrease in embolic events with early surgery. Thus, firm conclusions cannot be drawn from this trial on the effect of early surgery on mor- tality, given the small sample size of the study. In addition, patients in this trial were young and had limited comorbidity based on a EuroSCORE, a calculated risk of surgical mortality (http://www.euroscore.org), a low prevalence of S aureus IE, and lower mortality compared with most contemporary patient cohorts. Moreover, many patients had signs of embolization (a Class IIa indication for surgery) before randomization. Data from nonrandomized trials from a single-center experience250 and an international collaboration251 support the notion252 that early valve surgery may not be beneficial in all patients with native or PVE caused by S aureus. Over several decades, expert panels have relied on data from observational studies to make recommendations on the indications for early surgery. Despite the availability of new studies, the indications for surgery have not changed appre- ciably over time.18 Considering that observational studies are prone to bias and confounding, researchers have used regres- sion analysis and calculated propensity scores to adjust for prognostically important baseline differences between surgi- cal and medical patients.14,253 examin- ing the association between valve surgery and outcome in left-sided IE using propensity score analysis, however, have demonstrated conflicting results, likely because of the use of different analytical approaches. 