Infective endocarditis (IE) is a deadly disease and the incidence is increasing. An important initial assessment of patients with IE includes whether surgical treatment is indicated; yet, appropriate data to guide this assessment do not exist. The ASTERIx study will assess whether a surgical approach in addition to medical care for treatment of IE is superior to medical care alone. In total, 496 patients will be included in the study over four years. The study is event-driven and will require at least 240 events. The study will assess the primary composite outcome of death, embolization, relapse of IE, new heart failure or reinfection. Study participants who survive to discharge will be followed by routine clinical check-ups at one- and four-weeks post-discharge and at three months. Additionally a 12-month study follow-up is planned. The investigators will also conduct a small substudy to assess the frequency of silent emboli.